diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/lib/SCST/SCST.pm b/scstadmin/scstadmin.sysfs/scst-0.9.10/lib/SCST/SCST.pm
index 164eda796..dc2748c40 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/lib/SCST/SCST.pm
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/lib/SCST/SCST.pm
@@ -414,7 +414,7 @@ sub new {
 sub scstVersion {
 	my $self = shift;
 
-	my $attributes = $self->scstAttributes();
+	my ($attributes, $errorString) = $self->scstAttributes();
 
 	return undef if (!defined($attributes));
 	return $$attributes{'version'}->{'value'};
@@ -427,8 +427,7 @@ sub scstAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = SCST_ROOT_DIR();
 	if (!(opendir $pHandle, $_path)) {
-		$self->{'err_string'} = "scstAttributes(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "scstAttributes(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -454,9 +453,8 @@ sub scstAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "scsiAttributes(): Unable to read ".
-					  "scst attribute '$attribute': $!";
-					return undef;
+					return (undef, "scsiAttributes(): Unable to read ".
+					  "scst attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -510,7 +508,7 @@ sub scstAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setAttrFailed {
@@ -561,11 +559,11 @@ sub drivers {
 			}
 			close $dHandle;
 		} else {
-			$self->{'err_string'} = "drivers(): Unable to read directory '$_path': $!";
+			return (undef, "drivers(): Unable to read directory '$_path': $!");
 		}
 	}
 
-	return \@_drivers;
+	return (\@_drivers, undef);
 }
 
 
@@ -573,7 +571,7 @@ sub targets {
 	my $self = shift;
 	my $driver = shift;
 
-	return undef if (!defined($driver));
+	return (undef, "Too few arguments") if (!defined($driver));
 
 	my $tHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver);
@@ -591,15 +589,16 @@ sub targets {
 		}
 		close $tHandle;
 		@targets = sort(@targets);
-		return \@targets;
+		return (\@targets, undef);
 	}
+	my $errorString;
 	if ($self->driverExists($driver) != TRUE) {
-		$self->{'err_string'} = "targets(): Driver '$driver' is not available";
+		$errorString = "targets(): Driver '$driver' is not available";
 	} else {
-		$self->{'err_string'} = "targets(): Unable to read directory '$_path': $!";
+		$errorString = "targets(): Unable to read directory '$_path': $!";
 	}
 
-	return undef;
+	return (undef, $errorString);
 }
 
 sub groups {
@@ -607,7 +606,7 @@ sub groups {
 	my $driver = shift;
 	my $target = shift;
 
-	return undef if (!defined($driver) || !defined($target));
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target));
 
 	my $gHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target,
@@ -625,17 +624,18 @@ sub groups {
 			}
 		}
 		close $gHandle;
-		return \@groups;
+		return (\@groups, undef);
 	}
 
+	my $errorString;
 	if ($self->driverExists($driver) != TRUE) {
-		$self->{'err_string'} = "groups(): Driver '$driver' is not available";
+		$errorString = "groups(): Driver '$driver' is not available";
 	} elsif ($self->targetExists($driver, $target) != TRUE) {
-		$self->{'err_string'} = "groups(): Target '$target' is not available";
+		$errorString = "groups(): Target '$target' is not available";
 	} else {
-		$self->{'err_string'} = "groups(): Unable to read directory '$_path': $!";
+		$errorString = "groups(): Unable to read directory '$_path': $!";
 	}
-	return undef;
+	return (undef, $errorString);
 }
 
 sub initiators {
@@ -645,23 +645,24 @@ sub initiators {
 	my $group = shift;
 	my @initiators;
 
-	return undef if (!defined($driver) || !defined($target) ||
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target) ||
 			 !defined($group));
 
 	my $iHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target, SCST_GROUPS,
 			      $group, SCST_INITIATORS);
 	if (!(opendir $iHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "initiators(): Driver '$driver' is not available";
+			$errorString = "initiators(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "initiators(): Target '$target' is not available";
+			$errorString = "initiators(): Target '$target' is not available";
 		} elsif ($self->groupExists($driver, $target, $group) != TRUE) {
-			$self->{'err_string'} = "initiators(): Group '$group' does not exist";
+			$errorString = "initiators(): Group '$group' does not exist";
 		} else {
-			$self->{'err_string'} = "initiators(): Unable to read directory '$_path': $!";
+			$errorString = "initiators(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $initiator (readdir($iHandle)) {
@@ -673,7 +674,7 @@ sub initiators {
 
 	close $iHandle;
 
-	return \@initiators;
+	return (\@initiators, undef);
 }
 
 sub luns {
@@ -682,7 +683,7 @@ sub luns {
 	my $target = shift;
 	my $group = shift;
 
-	return undef if (!defined($driver) || !defined($target));
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target));
 
 	my $_path;
 
@@ -697,16 +698,17 @@ sub luns {
 	my $lHandle = new IO::Handle;
 
 	if (!(opendir $lHandle, $_path)) {
+		my $errorString;
 		if (defined($group) && $self->groupExists($driver, $target, $group) != TRUE) {
-			$self->{'err_string'} = "initiators(): Group '$group' does not exist";
+			$errorString = "initiators(): Group '$group' does not exist";
 		} elsif ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "luns(): Driver '$driver' is not available";
+			$errorString = "luns(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "luns(): Target '$target' is not available";
+			$errorString = "luns(): Target '$target' is not available";
 		} else {
-			$self->{'err_string'} = "luns(): Unable to read directory '$_path': $!";
+			$errorString = "luns(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	my %luns;
@@ -720,8 +722,7 @@ sub luns {
 			my $_lHandle = new IO::Handle;
 
 			if (!(opendir $_lHandle, $lPath)) {
-				$self->{'err_string'} = "luns(): Unable to read directory '$lPath': $!";
-				return undef;
+				return (undef, "luns(): Unable to read directory '$lPath': $!");
 			}
 
 			foreach my $attribute (readdir($_lHandle)) {
@@ -740,7 +741,7 @@ sub luns {
 
 	close $lHandle;
 
-	return \%luns;
+	return (\%luns, undef);
 }
 
 sub aluaAttributes {
@@ -750,8 +751,7 @@ sub aluaAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = SCST_DEV_GROUP_DIR();
 	if (!(opendir $pHandle, $_path)) {
-		$self->{'err_string'} = "deviceGroupsAttributes(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "deviceGroupsAttributes(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -768,8 +768,7 @@ sub aluaAttributes {
 			my $io = new IO::File $pPath, O_RDONLY;
 
 			if (!$io) {
-				$self->{'err_string'} = "deviceGroupsAttributes(): Unable to read device attribute '$attribute': $!";
-				return undef;
+				return (undef, "deviceGroupsAttributes(): Unable to read device attribute '$attribute': $!");
 			}
 
 			my $value = <$io>;
@@ -795,7 +794,7 @@ sub aluaAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub deviceGroups {
@@ -805,8 +804,7 @@ sub deviceGroups {
 	my $dHandle = new IO::Handle;
 	my $_path = SCST_DEV_GROUP_DIR();
 	if (!(opendir $dHandle, $_path)) {
-		$self->{'err_string'} = "deviceGroups(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "deviceGroups(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $group (readdir($dHandle)) {
@@ -819,7 +817,7 @@ sub deviceGroups {
 
 	close $dHandle;
 
-	return \@groups;
+	return (\@groups, undef);
 }
 
 sub deviceGroupDevices {
@@ -827,17 +825,18 @@ sub deviceGroupDevices {
 	my $group = shift;
 	my @devices;
 
-	return undef if (!defined($group));
+	return (undef, "Too few arguments") if (!defined($group));
 
 	my $dHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group, SCST_DG_DEVICES);
 	if (!(opendir $dHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "deviceGroupDevices(): Device group '$group' does not exist";
+			$errorString = "deviceGroupDevices(): Device group '$group' does not exist";
 		} else {
-			$self->{'err_string'} = "deviceGroupDevices(): Unable to read directory '$_path': $!";
+			$errorString = "deviceGroupDevices(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $device (readdir($dHandle)) {
@@ -850,7 +849,7 @@ sub deviceGroupDevices {
 
 	close $dHandle;
 
-	return \@devices;
+	return (\@devices, undef);
 }
 
 sub targetGroups {
@@ -858,17 +857,18 @@ sub targetGroups {
 	my $group = shift;
 	my @tgroups;
 
-	return undef if (!defined($group));
+	return (undef, "Too few arguments") if (!defined($group));
 
 	my $dHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group, SCST_DG_TGROUPS);
 	if (!(opendir $dHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroups(): Device group '$group' does not exist";
+			$errorString = "targetGroups(): Device group '$group' does not exist";
 		} else {
-			$self->{'err_string'} = "targetGroups(): Unable to read directory '$_path': $!";
+			$errorString = "targetGroups(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $tgroup (readdir($dHandle)) {
@@ -881,7 +881,7 @@ sub targetGroups {
 
 	close $dHandle;
 
-	return \@tgroups;
+	return (\@tgroups, undef);
 }
 
 sub targetGroupTargets {
@@ -890,19 +890,20 @@ sub targetGroupTargets {
 	my $tgroup = shift;
 	my @targets;
 
-	return undef if (!defined($group) || !defined($tgroup));
+	return (undef, "Too few arguments") if (!defined($group) || !defined($tgroup));
 
 	my $dHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group, SCST_DG_TGROUPS, $tgroup);
 	if (!(opendir $dHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargets(): Device group '$group' does not exist";
+			$errorString = "targetGroupTargets(): Device group '$group' does not exist";
 		} elsif ($self->targetGroupExists($group, $tgroup) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargets(): Target group '$tgroup' does not exist";
+			$errorString = "targetGroupTargets(): Target group '$tgroup' does not exist";
 		} else {
-			$self->{'err_string'} = "targetGroupTargets(): Unable to read directory '$_path': $!";
+			$errorString = "targetGroupTargets(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $tgt (readdir($dHandle)) {
@@ -917,7 +918,7 @@ sub targetGroupTargets {
 
 	@targets = sort(@targets);
 
-	return \@targets;
+	return (\@targets, undef);
 }
 
 sub driverExists {
@@ -926,7 +927,7 @@ sub driverExists {
 
 	return FALSE if (!defined($driver));
 
-	my $drivers = $self->drivers();
+	my ($drivers, $errorString) = $self->drivers();
 
 	return SCST_C_FATAL_ERROR if (!defined($drivers));
 
@@ -943,7 +944,7 @@ sub driverDynamicAttributes {
 	my %attributes;
 	my $available;
 
-	return undef if (!defined($driver));
+	return (undef, "Too few arguments") if (!defined($driver));
 
 	if (new_sysfs_interface()) {
 		my $io = new IO::File make_path(SCST_TARGETS_DIR(), $driver,
@@ -960,14 +961,15 @@ sub driverDynamicAttributes {
 						SCST_MGMT_IO), O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->driverExists($driver) != TRUE) {
-				$self->{'err_string'} = "driverDynamicAttributes(): Driver '$driver' ".
+				$errorString = "driverDynamicAttributes(): Driver '$driver' ".
 				    "is not available";
 			} else {
-				$self->{'err_string'} = "driverDynamicAttributes(): Unable to open mgmt ".
+				$errorString = "driverDynamicAttributes(): Unable to open mgmt ".
 				    "interface for driver '$driver': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -987,7 +989,7 @@ sub driverDynamicAttributes {
 		}
 	}
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub checkDriverDynamicAttributes {
@@ -995,7 +997,7 @@ sub checkDriverDynamicAttributes {
 	my $driver = shift;
 	my $check = shift;
 
-	my $available = $self->driverDynamicAttributes($driver);
+	my ($available, $errorString) = $self->driverDynamicAttributes($driver);
 
 	if (!defined($available)) {
 		my $rc = $self->driverExists($driver);
@@ -1143,10 +1145,10 @@ sub targetType {
 	my $driver = shift;
 	my $target = shift;
 
-	return undef if (!defined($driver) || !defined($target));
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target));
 
 	if ($self->driverIsVirtualCapable($driver)) {
-		my $attribs = $self->targetAttributes($driver, $target);
+		my ($attribs, $errorString) = $self->targetAttributes($driver, $target);
 
 		if (defined($$attribs{'hw_target'}) &&
 		    ($$attribs{'hw_target'}->{'value'} == TRUE)) {
@@ -1223,7 +1225,7 @@ sub targetDynamicAttributes {
 	my %attributes;
 	my $available;
 
-	return undef if (!defined($driver));
+	return (undef, "Too few arguments") if (!defined($driver));
 
 	if (new_sysfs_interface()) {
 		my $io = new IO::File make_path(SCST_TARGETS_DIR(), $driver,
@@ -1240,14 +1242,15 @@ sub targetDynamicAttributes {
 						SCST_MGMT_IO), O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->driverExists($driver) != TRUE) {
-				$self->{'err_string'} = "targetDynamicAttributes(): Driver '$driver' ".
+				$errorString = "targetDynamicAttributes(): Driver '$driver' ".
 				    "is not available";
 			} else {
-				$self->{'err_string'} = "targetDynamicAttributes(): Unable to open mgmt ".
+				$errorString = "targetDynamicAttributes(): Unable to open mgmt ".
 				    "interface for driver '$driver': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -1267,7 +1270,7 @@ sub targetDynamicAttributes {
 		}
 	}
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub checkTargetDynamicAttributes {
@@ -1275,7 +1278,7 @@ sub checkTargetDynamicAttributes {
 	my $driver = shift;
 	my $check = shift;
 
-	my $available = $self->targetDynamicAttributes($driver);
+	my ($available, $errorString) = $self->targetDynamicAttributes($driver);
 
 	if (!defined($available)) {
 		my $rc = $self->driverExists($driver);
@@ -1409,7 +1412,7 @@ sub removeVirtualTarget {
 	# case for e.g. the 'scst_local' driver.
 	$self->enableTarget($driver, $target, FALSE);
 
-	my $sessions = $self->sessions($driver, $target);
+	my ($sessions, $errorString) = $self->sessions($driver, $target);
 
 	my %can_close;
 	foreach my $session (keys %{$sessions}) {
@@ -1424,7 +1427,7 @@ sub removeVirtualTarget {
 		my $has_sessions = 1;
 		my $now = time();
 		while ($has_sessions && (($now + $TIMEOUT) > time())) {
-			$sessions = $self->sessions($driver, $target);
+			($sessions, $errorString) = $self->sessions($driver, $target);
 
 			foreach my $session (keys %can_close) {
 				if (!defined($$sessions{$session})) {
@@ -1481,7 +1484,7 @@ sub groupExists {
 
 	return FALSE if (!defined($driver) || !defined($target) || !defined($group));
 
-	my $groups = $self->groups($driver, $target);
+	my ($groups, $errorString) = $self->groups($driver, $target);
 
 	if (!defined($groups)) {
 		my $rc = $self->targetExists($driver, $target);
@@ -1508,7 +1511,7 @@ sub initiatorExists {
 	return FALSE if (!defined($driver) || !defined($target) ||
 			 !defined($group) || !defined($initiator));
 
-	my $initiators = $self->initiators($driver, $target, $group);
+	my ($initiators, $errorString) = $self->initiators($driver, $target, $group);
 
 	if (!defined($initiators)) {
 		my $rc = $self->groupExists($driver, $target, $group);
@@ -1535,7 +1538,7 @@ sub lunExists {
 	return FALSE if (!defined($driver) || !defined($target) ||
 			 !defined($lun));
 
-	my $luns = $self->luns($driver, $target, $group);
+	my ($luns, $errorString) = $self->luns($driver, $target, $group);
 
 	if (!defined($luns)) {
 		my $rc = $self->driverExists($driver);
@@ -1763,10 +1766,10 @@ sub addDeviceGroupDevice {
 	return $rc if ($rc > 1);
 
 	# Check all device groups for this device
-	my $dgroups = $self->deviceGroups();
+	my ($dgroups, $errorString) = $self->deviceGroups();
 
 	foreach my $dgroup (@{$dgroups}) {
-		my $devs = $self->deviceGroupDevices($dgroup);
+		my ($devs, $errorString) = $self->deviceGroupDevices($dgroup);
 
 		foreach my $dev (@{$devs}) {
 			return SCST_C_DGRP_DEVICE_OTHER if ($dev eq $device);
@@ -2411,7 +2414,7 @@ sub replaceLun {
 	return SCST_C_LUN_BAD_ATTRIBUTES if ($rc == TRUE);
 	return $rc if ($rc > 1);
 
-	my $luns = $self->luns($driver, $target, $group);
+	my ($luns, $errorString) = $self->luns($driver, $target, $group);
 
 	return SCST_C_LUN_DEV_EXISTS if ($$luns{$lun} eq $device);
 
@@ -2543,8 +2546,7 @@ sub devices {
 	my $_path = new_sysfs_interface() || !defined($handler) ?
 	    SCST_DEVICES_DIR() : make_path(SCST_HANDLERS_DIR(), $handler);
 	if (!(opendir $dHandle, $_path)) {
-		$self->{'err_string'} = "devices(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "devices(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $device (readdir($dHandle)) {
@@ -2560,7 +2562,7 @@ sub devices {
 
 	close $dHandle;
 
-	return \@devices;
+	return (\@devices, undef);
 }
 
 sub deviceOpen {
@@ -2569,7 +2571,7 @@ sub deviceOpen {
 
 	return FALSE if (!defined($device));
 
-	my $devices = $self->devices();
+	my ($devices, $errorString) = $self->devices();
 
 	return SCST_C_FATAL_ERROR if (!defined($devices));
 
@@ -2588,15 +2590,16 @@ sub deviceAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEVICES_DIR(), $device);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceOpen($device) != TRUE) {
-			$self->{'err_string'} = "deviceAttributes(): Device '$device' is not open";
+			$errorString = "deviceAttributes(): Device '$device' is not open";
 		} else {
-			$self->{'err_string'} = "deviceAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "deviceAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
-	my $dca = $self->deviceCreateAttributes($self->deviceHandler($device));
+	my ($dca, $errorString) = $self->deviceCreateAttributes($self->deviceHandler($device));
 
 	foreach my $attribute (readdir($pHandle)) {
 		next if ($attribute eq '.' || $attribute eq '..' ||
@@ -2660,9 +2663,8 @@ sub deviceAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "deviceAttributes(): Unable to read ".
-					  "device attribute '$attribute': $!";
-					return undef;
+					return (undef, "deviceAttributes(): Unable to read ".
+					  "device attribute '$attribute': $!");
 				}
 
 				my ($value, $is_key) = split("\n", _sysread($io) , 2);
@@ -2703,7 +2705,7 @@ sub deviceAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub driverAttributes {
@@ -2714,12 +2716,13 @@ sub driverAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "driverAttributes(): Driver '$driver' is not available";
+			$errorString = "driverAttributes(): Driver '$driver' is not available";
 		} else {
-			$self->{'err_string'} = "driverAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "driverAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -2745,9 +2748,8 @@ sub driverAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "driverAttributes(): Unable to read ".
-					  "driver attribute '$attribute': $!";
-					return undef;
+					return (undef, "driverAttributes(): Unable to read ".
+					  "driver attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -2803,7 +2805,7 @@ sub driverAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setDriverAttribute {
@@ -2842,19 +2844,20 @@ sub targetAttributes {
 	my $target = shift;
 	my %attributes;
 
-	return undef if (!defined($driver) || !defined($target));
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target));
 
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "targetAttributes(): Driver '$driver' is not available";
+			$errorString = "targetAttributes(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "targetAttributes(): Target '$target' is not available";
+			$errorString = "targetAttributes(): Target '$target' is not available";
 		} else {
-			$self->{'err_string'} = "targetAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "targetAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -2874,8 +2877,7 @@ sub targetAttributes {
 			my $_session_path = make_path($_path, $attribute);
 			my $pSessHandle = new IO::Handle;
 			if (!(opendir $pSessHandle, $_session_path)) {
-				$self->{'err_string'} = "targetAttributes(): Unable to read directory '$_session_path': $!";
-				return undef;
+				return (undef, "targetAttributes(): Unable to read directory '$_session_path': $!");
 			}
 			my $key = 0;
 			foreach my $e (readdir($pSessHandle)) {
@@ -2902,9 +2904,8 @@ sub targetAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "targetAttributes(): Unable to read ".
-					  "target attribute '$attribute': $!";
-					return undef;
+					return (undef, "targetAttributes(): Unable to read ".
+					  "target attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -2938,7 +2939,7 @@ sub targetAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setTargetAttribute {
@@ -2999,16 +3000,17 @@ sub groupAttributes {
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target, SCST_GROUPS,
 			      $group);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "groupAttributes(): Driver '$driver' is not available";
+			$errorString = "groupAttributes(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "groupAttributes(): Target '$target' is not available";
+			$errorString = "groupAttributes(): Target '$target' is not available";
 		} elsif ($self->groupExists($driver, $target, $group) != TRUE) {
-			$self->{'err_string'} = "groupAttributes(): Group '$group' does not exist";
+			$errorString = "groupAttributes(): Group '$group' does not exist";
 		} else {
-			$self->{'err_string'} = "groupAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "groupAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3036,9 +3038,8 @@ sub groupAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "groupAttributes(): Unable to read ".
-					  "group attribute '$attribute': $!";
-					return undef;
+					return (undef, "groupAttributes(): Unable to read ".
+					  "group attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3072,7 +3073,7 @@ sub groupAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setGroupAttribute {
@@ -3131,6 +3132,7 @@ sub lunAttributes {
 	my $target = shift;
 	my $lun = shift;
 	my $group = shift;
+	my $errorString;
 	my %attributes;
 
 	my ($_path, $luncrattr);
@@ -3138,28 +3140,28 @@ sub lunAttributes {
 	if (defined($group)) {
 		$_path = make_path(SCST_TARGETS_DIR(), $driver, $target,
 				   SCST_GROUPS, $group, SCST_LUNS, $lun);
-		$luncrattr = $self->lunCreateAttributes($driver, $target,
-							$group);
+		($luncrattr, $errorString) =
+		    $self->lunCreateAttributes($driver, $target, $group);
 	} else {
 		$_path = make_path(SCST_TARGETS_DIR(), $driver, $target,
 				   SCST_LUNS, $lun);
-		$luncrattr = $self->lunCreateAttributes($driver, $target);
+		($luncrattr, $errorString) = $self->lunCreateAttributes($driver, $target);
 	}
 
 	my $pHandle = new IO::Handle;
 	if (!(opendir $pHandle, $_path)) {
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "lunAttributes(): Driver '$driver' is not available";
+			$errorString = "lunAttributes(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "lunAttributes(): Target '$target' is not available";
+			$errorString = "lunAttributes(): Target '$target' is not available";
 		} elsif (defined($group) && $self->groupExists($driver, $target, $group) != TRUE) {
-			$self->{'err_string'} = "lunAttributes(): Group '$group' does not exist";
+			$errorString = "lunAttributes(): Group '$group' does not exist";
 		} elsif ($self->lunExists($driver, $target, $lun, $group) != TRUE) {
-			$self->{'err_string'} = "lunAttributes(): LUN '$lun' does not exist";
+			$errorString = "lunAttributes(): LUN '$lun' does not exist";
 		} else {
-			$self->{'err_string'} = "lunAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "lunAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3191,9 +3193,8 @@ sub lunAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "lunAttributes(): Unable to read ".
-					  "lun attribute '$attribute': $!";
-					return undef;
+					return (undef, "lunAttributes(): Unable to read ".
+					  "lun attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3229,7 +3230,7 @@ sub lunAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setLunAttribute {
@@ -3287,7 +3288,7 @@ sub setLunAttribute {
 	    if (!$rc);
 	return $rc if ($rc > 1);
 
-	my $attributes = $self->lunAttributes($driver, $target, $lun, $group);
+	my ($attributes, $errorString) = $self->lunAttributes($driver, $target, $lun, $group);
 
 	return SCST_C_LUN_BAD_ATTRIBUTES if (!defined($$attributes{$attribute}));
 	return SCST_C_LUN_ATTRIBUTE_STATIC if ($$attributes{$attribute}->{'static'});
@@ -3307,18 +3308,19 @@ sub initiatorAttributes {
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target, SCST_GROUPS,
 			      $group, SCST_INITIATORS, $initiator);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "initiatorAttributes(): Driver '$driver' is not available";
+			$errorString = "initiatorAttributes(): Driver '$driver' is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "initiatorAttributes(): Target '$target' is not available";
+			$errorString = "initiatorAttributes(): Target '$target' is not available";
 		} elsif ($self->groupExists($driver, $target, $group) != TRUE) {
-			$self->{'err_string'} = "initiatorAttributes(): Group '$group' does not exist";
+			$errorString = "initiatorAttributes(): Group '$group' does not exist";
 		} elsif ($self->initiatorExists($driver, $target, $group, $initiator) != TRUE) {
-			$self->{'err_string'} = "initiatorAttributes(): Initiator '$initiator' does not exist";
+			$errorString = "initiatorAttributes(): Initiator '$initiator' does not exist";
 		} else {
-			$self->{'err_string'} = "initiatorAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "initiatorAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3345,9 +3347,8 @@ sub initiatorAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "initiatorAttributes(): Unable to read ".
-					  "initiator attribute '$attribute': $!";
-					return undef;
+					return (undef, "initiatorAttributes(): Unable to read ".
+					  "initiator attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3381,7 +3382,7 @@ sub initiatorAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setInitiatorAttribute {
@@ -3437,12 +3438,13 @@ sub deviceGroupAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "deviceGroupAttributes(): Device group '$group' does not exist";
+			$errorString = "deviceGroupAttributes(): Device group '$group' does not exist";
 		} else {
-			$self->{'err_string'} = "deviceGroupAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "deviceGroupAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3467,9 +3469,8 @@ sub deviceGroupAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "deviceGroupAttributes(): Unable to read ".
-					  "device group attribute '$attribute': $!";
-					return undef;
+					return (undef, "deviceGroupAttributes(): Unable to read ".
+					  "device group attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3503,7 +3504,7 @@ sub deviceGroupAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub targetGroupAttributes {
@@ -3515,14 +3516,15 @@ sub targetGroupAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group, SCST_DG_TGROUPS, $tgroup);
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroupAttributes(): Device group '$group' does not exist";
+			$errorString = "targetGroupAttributes(): Device group '$group' does not exist";
 		} elsif ($self->targetGroupExists($group, $tgroup) != TRUE) {
-			$self->{'err_string'} = "targetGroupAttributes(): Target Group '$tgroup' does not exist";
+			$errorString = "targetGroupAttributes(): Target Group '$tgroup' does not exist";
 		} else {
-			$self->{'err_string'} = "targetGroupAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "targetGroupAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3547,9 +3549,8 @@ sub targetGroupAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "targetGroupAttributes(): Unable to read ".
-					  "target group attribute '$attribute': $!";
-					return undef;
+					return (undef, "targetGroupAttributes(): Unable to read ".
+					  "target group attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3583,7 +3584,7 @@ sub targetGroupAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub targetGroupTargetAttributes {
@@ -3597,20 +3598,21 @@ sub targetGroupTargetAttributes {
 	my $pHandle = new IO::Handle;
 	my $_path = make_path(SCST_DEV_GROUP_DIR(), $group, SCST_DG_TGROUPS, $tgroup, $tgt);
 	if (-l $_path && !$local_tgt) {
-		return \%attributes;
+		return (\%attributes, undef);
 	}
 
 	if (!(opendir $pHandle, $_path)) {
+		my $errorString;
 		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargetAttributes(): Device group '$group' does not exist";
+			$errorString = "targetGroupTargetAttributes(): Device group '$group' does not exist";
 		} elsif ($self->targetGroupExists($group, $tgroup) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargetAttributes(): Target Group '$tgroup' does not exist";
+			$errorString = "targetGroupTargetAttributes(): Target Group '$tgroup' does not exist";
 		} elsif ($self->targetGroupTargetExists($group, $tgroup, $tgt) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargetAttributes(): Target '$tgt' does not exist";
+			$errorString = "targetGroupTargetAttributes(): Target '$tgt' does not exist";
 		} else {
-			$self->{'err_string'} = "targetGroupTargetAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "targetGroupTargetAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($pHandle)) {
@@ -3636,9 +3638,8 @@ sub targetGroupTargetAttributes {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "targetGroupTargetAttributes(): Unable to read ".
-					  "target group target attribute '$attribute': $!";
-					return undef;
+					return (undef, "targetGroupTargetAttributes(): Unable to read ".
+					  "target group target attribute '$attribute': $!");
 				}
 
 				my $value = <$io>;
@@ -3672,7 +3673,7 @@ sub targetGroupTargetAttributes {
 
 	close $pHandle;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub setAluaAttribute {
@@ -3815,8 +3816,7 @@ sub handlers {
 	my $hHandle = new IO::Handle;
 	my $_path = SCST_HANDLERS_DIR();
 	if (!(opendir $hHandle, $_path)) {
-		$self->{'err_string'} = "handlers(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "handlers(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $handler (readdir($hHandle)) {
@@ -3829,7 +3829,7 @@ sub handlers {
 
 	close $hHandle;
 
-	return \@handlers;
+	return (\@handlers, undef);
 }
 
 sub handlerExists {
@@ -3838,7 +3838,7 @@ sub handlerExists {
 
 	return FALSE if (!defined($handler));
 
-	my $handlers = $self->handlers();
+	my ($handlers, $errorString) = $self->handlers();
 
 	return SCST_C_FATAL_ERROR if (!defined($handlers));
 
@@ -3883,17 +3883,19 @@ sub handlerAttributes {
 	my $handler = shift;
 	my %attributes;
 
-	$attributes{'devices'}->{'value'} = devices($self, $handler);
+	my ($a, $errorString) = devices($self, $handler);
+	$attributes{'devices'}->{'value'} = $a;
 
 	my $hHandle = new IO::Handle;
 	my $_path = make_path(SCST_HANDLERS_DIR(), $handler);
 	if (!(opendir $hHandle, $_path)) {
+		my $errorString;
 		if ($self->handlerExists($handler) != TRUE) {
-			$self->{'err_string'} = "handlerAttributes(): Handler '$handler' is not available";
+			$errorString = "handlerAttributes(): Handler '$handler' is not available";
 		} else {
-			$self->{'err_string'} = "handlerAttributes(): Unable to read directory '$_path': $!";
+			$errorString = "handlerAttributes(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $attribute (readdir($hHandle)) {
@@ -3915,9 +3917,8 @@ sub handlerAttributes {
 		my $io = new IO::File $path, O_RDONLY;
 
 		if (!$io) {
-			$self->{'err_string'} = "handlerAttributes(): Unable to read handler attribute ".
-			  "'$attribute': $!";
-			return undef;
+			return (undef, "handlerAttributes(): Unable to read handler attribute ".
+			  "'$attribute': $!");
 		}
 
 		my $value = <$io>;
@@ -3982,14 +3983,14 @@ sub handlerAttributes {
 
 	$attributes{'devices'}->{'static'} = TRUE;
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub deviceExists {
 	my $self = shift;
 	my $device = shift;
 
-	my $handlers = $self->handlers();
+	my ($handlers, $errorString) = $self->handlers();
 
 	return SCST_C_FATAL_ERROR if (!defined($handlers));
 
@@ -4005,7 +4006,7 @@ sub handlerDeviceExists {
 	my $handler = shift;
 	my $device = shift;
 
-	my $devices = $self->devicesByHandler($handler);
+	my ($devices, $errorString) = $self->devicesByHandler($handler);
 
 	if (!defined($devices)) {
 		my $rc = $self->handlerExists($handler);
@@ -4026,16 +4027,19 @@ sub devicesByHandler {
 	my $self = shift;
 	my $handler = shift;
 
-	my $attributes = $self->handlerAttributes($handler);
+	my ($attributes, $errorString) = $self->handlerAttributes($handler);
 
 	if (!defined($attributes)) {
+		my $errorString;
 		if ($self->handlerExists($handler) != TRUE) {
-			$self->{'err_string'} = "devicesByHandler(): Handler '$handler' is not available";
+			$errorString = "devicesByHandler(): Handler '$handler' is not available";
+		} else {
+			$errorString = "devicesByHandler() failed";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
-	return \@{$$attributes{'devices'}->{'value'}};
+	return (\@{$$attributes{'devices'}->{'value'}}, undef);
 }
 
 sub checkDeviceCreateAttributes {
@@ -4045,7 +4049,7 @@ sub checkDeviceCreateAttributes {
 
 	return FALSE if (!defined($check));
 
-	my $available = $self->deviceCreateAttributes($handler);
+	my ($available, $errorString) = $self->deviceCreateAttributes($handler);
 
 	if (!defined($available)) {
 		my $rc = $self->handlerExists($handler);
@@ -4089,14 +4093,15 @@ sub deviceCreateAttributes {
 						SCST_MGMT_IO), O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->handlerExists($handler) != TRUE) {
-				$self->{'err_string'} = "deviceCreateAttributes(): Handler '$handler' ".
+				$errorString = "deviceCreateAttributes(): Handler '$handler' ".
 				    "is not available";
 			} else {
-				$self->{'err_string'} = "deviceCreateAttributes(): Unable to open mgmt ".
+				$errorString = "deviceCreateAttributes(): Unable to open mgmt ".
 				    "interface for handler '$handler': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -4116,7 +4121,7 @@ sub deviceCreateAttributes {
 		}
 	}
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub openDevice {
@@ -4174,8 +4179,6 @@ sub openDevice {
 
 	return SCST_C_DEV_OPEN_FAIL if ($errno == EINVAL);
 
-	$self->{'err_string'} = "openDevice(): Unable to open mgmt interface for ".
-	    "handler '$handler': $errno";
 	return SCST_C_FATAL_ERROR;
 }
 
@@ -4218,8 +4221,6 @@ sub closeDevice {
 	return SCST_C_DEV_NO_DEVICE if ($rc != TRUE);
 	return $rc if ($rc > 1);
 
-	$self->{'err_string'} = "closeDevice(): Unable to open mgmt interface for handler ".
-	    "'$handler': $errno";
 	return SCST_C_FATAL_ERROR;
 }
 
@@ -4268,7 +4269,7 @@ sub checkTargetCreateAttributes {
 
 	return FALSE if (!defined($check));
 
-	my $available = $self->targetCreateAttributes($driver);
+	my ($available, $errorString) = $self->targetCreateAttributes($driver);
 
 	if (!defined($available)) {
 		my $rc = $self->driverExists($driver);
@@ -4311,14 +4312,15 @@ sub targetCreateAttributes {
 						SCST_MGMT_IO), O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->driverExists($driver) != TRUE) {
-				$self->{'err_string'} = "targetCreateAttributes(): Driver '$driver' ".
+				$errorString = "targetCreateAttributes(): Driver '$driver' ".
 				    "is not available";
 			} else {
-				$self->{'err_string'} = "targetCreateAttributes(): Unable to open driver mgmt ".
+				$errorString = "targetCreateAttributes(): Unable to open driver mgmt ".
 				    "interface for driver '$driver': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -4338,7 +4340,7 @@ sub targetCreateAttributes {
 		}
 	}
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub enableTarget {
@@ -4371,7 +4373,7 @@ sub deviceGroupExists {
 	my $self = shift;
 	my $group = shift;
 
-	my $groups = $self->deviceGroups();
+	my ($groups, $errorString) = $self->deviceGroups();
 
 	return SCST_C_FATAL_ERROR if (!defined($groups));
 
@@ -4387,13 +4389,9 @@ sub deviceGroupDeviceExists {
 	my $group = shift;
 	my $device = shift;
 
-	my $devices = $self->deviceGroupDevices($group);
+	my ($devices, $errorString) = $self->deviceGroupDevices($group);
 
 	if (!defined($devices)) {
-		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "deviceGroupDeviceExists(): Device group '$group' does not exist";
-			return undef;
-		}
 		return SCST_C_FATAL_ERROR;
 	}
 
@@ -4409,13 +4407,9 @@ sub targetGroupExists {
 	my $group = shift;
 	my $tgroup = shift;
 
-	my $tgroups = $self->targetGroups($group);
+	my ($tgroups, $errorString) = $self->targetGroups($group);
 
 	if (!defined($tgroups)) {
-		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroupExists(): Device group '$group' does not exist";
-			return undef;
-		}
 		return SCST_C_FATAL_ERROR;
 	}
 
@@ -4432,18 +4426,10 @@ sub targetGroupTargetExists {
 	my $tgroup = shift;
 	my $tgt = shift;
 
-	my $targets = $self->targetGroupTargets($group, $tgroup);
+	my ($targets, $errorString) = $self->targetGroupTargets($group, $tgroup);
 
 	if (!defined($targets)) {
-		if ($self->deviceGroupExists($group) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargetExists(): Device group '$group' does not exist";
-			return undef;
-		} elsif ($self->targetGroupExists($group, $tgroup) != TRUE) {
-			$self->{'err_string'} = "targetGroupTargetExists(): Target group '$tgroup' does not exist";
-			return undef;
-		} else {
-			return SCST_C_FATAL_ERROR;
-		}
+		return SCST_C_FATAL_ERROR;
 	}
 
 	foreach my $_tgt (@{$targets}) {
@@ -4462,7 +4448,7 @@ sub checkLunCreateAttributes {
 
 	return FALSE if (!defined($check));
 
-	my $available = $self->lunCreateAttributes($driver, $target, $group);
+	my ($available, $errorString) = $self->lunCreateAttributes($driver, $target, $group);
 
 	if (!defined($available)) {
 		my $rc = $self->driverExists($driver);
@@ -4510,9 +4496,8 @@ sub lunCreateAttributes {
 	if (new_sysfs_interface()) {
 		if (defined($group)) {
 			if ($self->groupExists($driver, $target, $group) != TRUE) {
-				$self->{'err_string'} = "lunCreateAttributes(): Group '$group' ".
-				    "does not exist";
-				return undef;
+				return ("lunCreateAttributes(): Group '$group' ".
+				    "does not exist");
 			}
 
 			$_path = make_path(SCST_TARGETS_DIR(), $driver, $target,
@@ -4542,20 +4527,21 @@ sub lunCreateAttributes {
 		my $io = new IO::File $_path, O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->driverExists($driver) != TRUE) {
-				$self->{'err_string'} = "lunCreateAttributes(): Driver '$driver' ".
+				$errorString = "lunCreateAttributes(): Driver '$driver' ".
 				    "is not available";
 			} elsif ($self->targetExists($driver, $target) != TRUE) {
-				$self->{'err_string'} = "lunCreateAttributes(): Target '$target' ".
+				$errorString = "lunCreateAttributes(): Target '$target' ".
 				    "is not available";
 			} elsif (defined($group) && $self->groupExists($driver, $target, $group) != TRUE) {
-				$self->{'err_string'} = "lunCreateAttributes(): Group '$group' ".
+				$errorString = "lunCreateAttributes(): Group '$group' ".
 				    "does not exist";
 			} else {
-				$self->{'err_string'} = "lunCreateAttributes(): Unable to open luns mgmt ".
+				$errorString = "lunCreateAttributes(): Unable to open luns mgmt ".
 				    "interface for group '$group': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -4574,7 +4560,7 @@ sub lunCreateAttributes {
 			}
 		}
 	}
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub checkInitiatorCreateAttributes {
@@ -4586,7 +4572,7 @@ sub checkInitiatorCreateAttributes {
 
 	return FALSE if (!defined($check));
 
-	my $available = $self->initiatorCreateAttributes($driver, $target, $group);
+	my ($available, $errorString) = $self->initiatorCreateAttributes($driver, $target, $group);
 
 	if (!defined($available)) {
 		my $rc = $self->driverExists($driver);
@@ -4636,21 +4622,21 @@ sub initiatorCreateAttributes {
 				O_RDONLY;
 
 		if (!$io) {
+			my $errorString;
 			if ($self->driverExists($driver) != TRUE) {
-				$self->{'err_string'} = "initiatorCreateAttributes(): Driver '$driver' ".
+				$errorString = "initiatorCreateAttributes(): Driver '$driver' ".
 				    "is not available";
 			} elsif ($self->targetExists($driver, $target) != TRUE) {
-				$self->{'err_string'} = "initiatorCreateAttributes(): Target '$target' ".
+				$errorString = "initiatorCreateAttributes(): Target '$target' ".
 				    "is not available";
-				return undef;
 			} elsif ($self->groupExists($driver, $target, $group) != TRUE) {
-				$self->{'err_string'} = "initiatorCreateAttributes(): Group '$group' ".
+				$errorString = "initiatorCreateAttributes(): Group '$group' ".
 				    "does not exist";
 			} else {
-				$self->{'err_string'} = "initiatorCreateAttributes(): Unable to open initiators mgmt ".
+				$errorString = "initiatorCreateAttributes(): Unable to open initiators mgmt ".
 				    "interface for group '$group': $!";
 			}
-			return undef;
+			return (undef, $errorString);
 		}
 
 		while (my $in = <$io>) {
@@ -4670,7 +4656,7 @@ sub initiatorCreateAttributes {
 		}
 	}
 
-	return \%attributes;
+	return (\%attributes, undef);
 }
 
 sub sessions {
@@ -4679,22 +4665,23 @@ sub sessions {
 	my $target = shift;
 	my %_sessions;
 
-	return undef if (!defined($driver) || !defined($target));
+	return (undef, "Too few arguments") if (!defined($driver) || !defined($target));
 
 	my $sHandle = new IO::Handle;
 	my $_path = make_path(SCST_TARGETS_DIR(), $driver, $target,
 			      SCST_SESSIONS);
 	if (!(opendir $sHandle, $_path)) {
+		my $errorString;
 		if ($self->driverExists($driver) != TRUE) {
-			$self->{'err_string'} = "sessions(): Driver '$driver' ".
+			$errorString = "sessions(): Driver '$driver' ".
 			    "is not available";
 		} elsif ($self->targetExists($driver, $target) != TRUE) {
-			$self->{'err_string'} = "sessions(): Target '$target' ".
+			$errorString = "sessions(): Target '$target' ".
 			    "is not available";
 		} else {
-			$self->{'err_string'} = "sessions(): Unable to read directory '$_path': $!";
+			$errorString = "sessions(): Unable to read directory '$_path': $!";
 		}
-		return undef;
+		return (undef, $errorString);
 	}
 
 	foreach my $session (readdir($sHandle)) {
@@ -4702,8 +4689,7 @@ sub sessions {
 		my $pHandle = new IO::Handle;
 		my $sPath = make_path($_path, $session);
 		if (!(opendir $pHandle, $sPath)) {
-			$self->{'err_string'} = "sessions(): Unable to read directory '$_path': $!";
-			return undef;
+			return (undef, "sessions(): Unable to read directory '$_path': $!");
 		}
 
 		foreach my $attribute (readdir($pHandle)) {
@@ -4739,9 +4725,9 @@ sub sessions {
 						my $io = new IO::File $pPath, O_RDONLY;
 
 						if (!$io) {
-							$self->{'err_string'} = "sessions(): Unable to read ".
-							  "session attribute '$attribute': $!";
-							return undef;
+							return (undef,
+								"sessions(): Unable to read ".
+								"session attribute '$attribute': $!");
 						}
 
 						my $value = <$io>;
@@ -4758,7 +4744,7 @@ sub sessions {
 	}
 	close $sHandle;
 
-	return \%_sessions;
+	return (\%_sessions, undef);
 }
 
 sub closeSession {
@@ -4767,7 +4753,7 @@ sub closeSession {
 	my $target = shift;
 	my $session = shift;
 
-	my $sessions = $self->sessions($driver, $target);
+	my ($sessions, $errorString) = $self->sessions($driver, $target);
 
 	return SCST_C_NO_SESSION if (!defined($$sessions{$session}));
 
@@ -4799,8 +4785,7 @@ sub sgvStats {
 	my $sHandle = new IO::Handle;
 	my $_path = SCST_SGV_DIR();
 	if (!(opendir $sHandle, $_path)) {
-		$self->{'err_string'} = "svgStats(): Unable to read directory '$_path': $!";
-		return undef;
+		return (undef, "svgStats(): Unable to read directory '$_path': $!");
 	}
 
 	foreach my $stat (readdir($sHandle)) {
@@ -4811,8 +4796,7 @@ sub sgvStats {
 		if (-d $sPath) {
 			my $lHandle = new IO::Handle;
 			if (!(opendir $lHandle, $sPath)) {
-				$self->{'err_string'} = "svgStats(): Unable to read directory '$sPath': $!";
-				return undef;
+				return (undef, "svgStats(): Unable to read directory '$sPath': $!");
 			}
 
 			foreach my $lief (readdir($lHandle)) {
@@ -4821,9 +4805,8 @@ sub sgvStats {
 				my $io = new IO::File $pPath, O_RDONLY;
 
 				if (!$io) {
-					$self->{'err_string'} = "sgvStats(): Unable to read ".
-					  "sgv stat '$stat/$lief': $!";
-					return undef;
+					return (undef, "sgvStats(): Unable to read ".
+					  "sgv stat '$stat/$lief': $!");
 				}
 
 				my $buffer;
@@ -4839,9 +4822,8 @@ sub sgvStats {
 			my $io = new IO::File $sPath, O_RDONLY;
 
 			if (!$io) {
-				$self->{'err_string'} = "sgvStats(): Unable to read ".
-				  "sgv stat '$stat': $!";
-				return undef;
+				return (undef, "sgvStats(): Unable to read ".
+					"sgv stat '$stat': $!");
 			}
 
 			my $buffer;
@@ -4855,20 +4837,14 @@ sub sgvStats {
 	}
 	close $sHandle;
 
-	return \%stats;
+	return (\%stats, undef);
 }
 
 sub errorString {
 	my $self = shift;
 	my $rc = shift;
 
-	return $VERBOSE_ERROR{$rc} if (defined($rc));
-	return undef if (!$self->{'err_string'});
-
-	my $string = $self->{'err_string'};
-	$self->{'err_string'} = undef;
-
-	return $string;
+	return defined($rc) ? $VERBOSE_ERROR{$rc} : undef;
 }
 
 # Read from the SCST sysfs file $1. Return either the data read or undef if
diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/02-scst-attr.t b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/02-scst-attr.t
index 2f91137a3..267423138 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/02-scst-attr.t
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/02-scst-attr.t
@@ -11,7 +11,7 @@ use SCST::SCST;
 
 sub getScstThreadCount {
     my $SCST = shift;
-    my $scstAttributes = $SCST->scstAttributes();
+    my ($scstAttributes, $errorString) = $SCST->scstAttributes();
     my $threadHash = $scstAttributes->{'threads'};
     return exists($threadHash->{'keys'}) ? $threadHash->{'keys'}->{'0'}->{'value'} : $threadHash->{'value'};
 }
diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/03-targets.t b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/03-targets.t
index 547ed82af..28db54d06 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/03-targets.t
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/03-targets.t
@@ -4,7 +4,7 @@ use strict;
 use Test;
 
 BEGIN {
-    plan tests => 181;
+    plan tests => 177;
 }
 
 use Data::Dumper;
@@ -13,17 +13,18 @@ use SCST::SCST;
 sub addTargets {
     my $SCST = shift;
 
-    ok($SCST->targets('no-such-driver'), undef);
-    ok($SCST->{'err_string'},
-       "targets(): Driver 'no-such-driver' is not available");
+    ok(Dumper($SCST->targets('no-such-driver')),
+       Dumper(undef, "targets(): Driver 'no-such-driver' is not available"));
 
-    my %drivers = map { $_ => 1 } @{$SCST->drivers()};
+    my ($drivers, $errorString) = $SCST->drivers();
+    my %drivers = map { $_ => 1 } @{$drivers};
     ok(exists($drivers{'iscsi'}));
     ok(exists($drivers{'scst_local'}));
 
     my $all_hw_tgt = 1;
-    for my $driver (@{$SCST->drivers()}) {
-	for my $target (@{$SCST->targets($driver)}) {
+    for my $driver (@{$drivers}) {
+	my ($targets, $errorString) = $SCST->targets($driver);
+	for my $target (@{$targets}) {
 	    if ($SCST->targetType($driver, $target) !=
 		$SCST::SCST::TGT_TYPE_HARDWARE) {
 		$all_hw_tgt = undef;
@@ -32,35 +33,36 @@ sub addTargets {
     }
     ok($all_hw_tgt);
 
-    ok(Dumper($SCST->targets()), Dumper(undef));
-    ok(Dumper($SCST->targets('no-such-driver')), Dumper(undef));
-    ok($SCST->{'err_string'},
-       "targets(): Driver 'no-such-driver' is not available");
-    ok(Dumper($SCST->targets('scst_local')), Dumper([]));
-    ok(Dumper($SCST->targets('iscsi')), Dumper([]));
+    ok(Dumper($SCST->targets()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targets('no-such-driver')),
+       Dumper(undef, "targets(): Driver 'no-such-driver' is not available"));
+    ok(Dumper($SCST->targets('scst_local')), Dumper([], undef));
+    ok(Dumper($SCST->targets('iscsi')), Dumper([], undef));
 
     ok($SCST->addVirtualTarget('no-such-driver', ''),
        $SCST->SCST_C_DRV_NO_DRIVER);
     ok($SCST->removeVirtualTarget('no-such-driver', ''),
        $SCST->SCST_C_DRV_NO_DRIVER);
     ok($SCST->addVirtualTarget('scst_local', 'local1'), 0);
-    ok(Dumper($SCST->targetType()), Dumper(undef));
-    ok(Dumper($SCST->targetType('scst_local')), Dumper(undef));
+    ok(Dumper($SCST->targetType()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targetType('scst_local')),
+       Dumper(undef, "Too few arguments"));
     ok($SCST->targetType('scst_local', 'no-such-target'),
        $SCST::SCST::TGT_TYPE_VIRTUAL);
     ok($SCST->targetType('scst_local', 'local1'),
        $SCST::SCST::TGT_TYPE_VIRTUAL);
-    ok(Dumper($SCST->targets('scst_local')), Dumper(['local1']));
+    ok(Dumper($SCST->targets('scst_local')), Dumper(['local1'], undef));
     ok($SCST->removeVirtualTarget('scst_local', 'local2'),
        $SCST->SCST_C_TGT_NO_TARGET);
-    ok(Dumper($SCST->targets('scst_local')), Dumper(['local1']));
+    ok(Dumper($SCST->targets('scst_local')), Dumper(['local1'], undef));
     ok($SCST->removeVirtualTarget('scst_local', 'local1'), 0);
-    ok(Dumper($SCST->targets('scst_local')), Dumper([]));
+    ok(Dumper($SCST->targets('scst_local')), Dumper([], undef));
     ok($SCST->addVirtualTarget('scst_local', 'local1',
 			       { 'session_name' => 'local1' }), 0);
     ok($SCST->addVirtualTarget('scst_local', 'local2',
 			       { 'session_name' => 'local2' }), 0);
-    ok(Dumper($SCST->targets('scst_local')), Dumper(['local1', 'local2']));
+    ok(Dumper($SCST->targets('scst_local')),
+       Dumper(['local1', 'local2'], undef));
 
     ok($SCST->targetExists(), 0);
     ok($SCST->targetExists('no-such-driver'), 0);
@@ -75,9 +77,10 @@ sub addTargets {
 sub sessTest {
     my $SCST = shift;
 
-    ok(Dumper($SCST->sessions()), Dumper(undef));
-    ok(Dumper($SCST->sessions('scst_local')), Dumper(undef));
-    my $s = $SCST->sessions('scst_local', 'local1');
+    ok(Dumper($SCST->sessions()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->sessions('scst_local')),
+       Dumper(undef, "Too few arguments"));
+    my ($s, $errorString) = $SCST->sessions('scst_local', 'local1');
     ok(Dumper(sort(keys(%$s))), Dumper('local1'));
     ok($s->{'local1'}->{'commands'}->{'value'}, '0');
 }
@@ -85,19 +88,22 @@ sub sessTest {
 sub driverDynamicAttributesTest {
     my $SCST = shift;
 
-    ok(Dumper($SCST->driverDynamicAttributes()), Dumper(undef));
-    ok(Dumper($SCST->driverDynamicAttributes('no-such-driver')), Dumper(undef));
-    ok($SCST->{'err_string'},
-       "driverDynamicAttributes(): Driver 'no-such-driver' is not available");
-    ok(Dumper($SCST->driverDynamicAttributes('scst_local')), Dumper({}));
+    ok(Dumper($SCST->driverDynamicAttributes()),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->driverDynamicAttributes('no-such-driver')),
+       Dumper(undef, "driverDynamicAttributes(): Driver 'no-such-driver' is " .
+	       "not available"));
+    ok(Dumper($SCST->driverDynamicAttributes('scst_local')),
+       Dumper({}, undef));
 }
 
 sub iniGrpTest {
     my $SCST = shift;
 
-    ok(Dumper($SCST->groups()), Dumper(undef));
-    ok(Dumper($SCST->groups('scst_local')), Dumper(undef));
-    ok(Dumper($SCST->groups('scst_local', 'local1')), Dumper([]));
+    ok(Dumper($SCST->groups()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->groups('scst_local')),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->groups('scst_local', 'local1')), Dumper([], undef));
 
     ok($SCST->addGroup(), $SCST->SCST_C_GRP_ADD_FAIL);
     ok($SCST->addGroup('no-such-driver', 'local1', 'group1'),
@@ -110,7 +116,7 @@ sub iniGrpTest {
     ok($SCST->addGroup('scst_local', 'local1', 'group2'), 0);
     ok($SCST->addGroup('scst_local', 'local1', 'group3'), 0);
     ok(Dumper($SCST->groups('scst_local', 'local1')),
-       Dumper(['group1', 'group2', 'group3']));
+       Dumper(['group1', 'group2', 'group3'], undef));
 
     ok($SCST->groupExists(), 0);
     ok($SCST->groupExists('no-such-driver', '', ''), 0);
@@ -128,7 +134,7 @@ sub iniGrpTest {
        $SCST->SCST_C_GRP_NO_GROUP);
     ok($SCST->removeGroup('scst_local', 'local1', 'group2'), 0);
     ok($SCST->removeGroup('scst_local', 'local1', 'group3'), 0);
-    ok(Dumper($SCST->groups('scst_local', 'local1')), Dumper([]));
+    ok(Dumper($SCST->groups('scst_local', 'local1')), Dumper([], undef));
 
     ok($SCST->addGroup('scst_local', 'local1', 'group1'), 0);
     ok($SCST->addInitiator('scst_local', 'local1', 'group1'),
@@ -143,11 +149,13 @@ sub iniGrpTest {
     ok($SCST->addInitiator('scst_local', 'local1', 'group1', 'ini2'), 0);
     ok($SCST->addInitiator('scst_local', 'local1', 'group1', 'ini1'),
        $SCST->SCST_C_GRP_INI_EXISTS);
-    ok(Dumper($SCST->initiators()), Dumper(undef));
-    ok(Dumper($SCST->initiators('scst_local')), Dumper(undef));
-    ok(Dumper($SCST->initiators('scst_local', 'local1')), Dumper(undef));
+    ok(Dumper($SCST->initiators()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->initiators('scst_local')),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->initiators('scst_local', 'local1')),
+       Dumper(undef, "Too few arguments"));
     ok(Dumper($SCST->initiators('scst_local', 'local1', 'group1')),
-       Dumper(['ini1', 'ini2']));
+       Dumper(['ini1', 'ini2'], undef));
 
     ok($SCST->initiatorExists(), 0);
     ok($SCST->initiatorExists('no-such-driver', '', '', ''), 0);
@@ -180,7 +188,8 @@ sub iniGrpTest {
     ok($SCST->removeInitiator('scst_local', 'local1', 'group1', 'ini2'), 0);
     ok($SCST->removeInitiator('scst_local', 'local1', 'group1', 'ini2'),
 	$SCST->SCST_C_GRP_NO_INI);
-    ok(Dumper($SCST->initiators('scst_local', 'local1', 'group1')), Dumper([]));
+    ok(Dumper($SCST->initiators('scst_local', 'local1', 'group1')),
+       Dumper([], undef));
     ok($SCST->removeGroup('scst_local', 'local1', 'group1'), 0);
 }
 
@@ -190,7 +199,7 @@ sub lunReadOnly {
     my $target = shift;
     my $lun = shift;
 
-    my $a = $SCST->lunAttributes($driver, $target, $lun);
+    my ($a, $errorString) = $SCST->lunAttributes($driver, $target, $lun);
     my $roHash = $a->{'read_only'};
     return exists($roHash->{'keys'}) ? $roHash->{'keys'}->{'0'}->{'value'} :
 	$roHash->{'value'};
@@ -207,6 +216,8 @@ sub lunTest {
        $SCST->SCST_C_DEV_OPEN_FAIL);
     ok($SCST->openDevice("vdisk_fileio", "disk01",
 			 { 'filename' => '/proc/cpuinfo' }), 0);
+    ok(Dumper($SCST->devicesByHandler("vdisk_fileio")),
+       Dumper(["disk01"], undef));
     ok($SCST->openDevice("vdisk_fileio", "disk01",
 			 { 'filename' => '/proc/cpuinfo' }),
        $SCST->SCST_C_DEV_EXISTS);
@@ -255,20 +266,18 @@ sub lunTest {
        $SCST->SCST_C_GRP_NO_GROUP);
     ok($SCST->lunExists('scst_local', 'local1', 0, 'group1'), 1);
 
-    ok(Dumper($SCST->luns()), Dumper(undef));
-    ok(Dumper($SCST->luns('scst_local')), Dumper(undef));
-    ok(Dumper($SCST->luns('no-such-driver', 'local1')), Dumper(undef));
-    ok($SCST->{'err_string'},
-       "luns(): Driver 'no-such-driver' is not available");
-    ok(Dumper($SCST->luns('scst_local', 'no-such-target')), Dumper(undef));
-    ok($SCST->{'err_string'},
-       "luns(): Target 'no-such-target' is not available");
+    ok(Dumper($SCST->luns()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->luns('scst_local')), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->luns('no-such-driver', 'local1')),
+       Dumper(undef, "luns(): Driver 'no-such-driver' is not available"));
+    ok(Dumper($SCST->luns('scst_local', 'no-such-target')),
+       Dumper(undef, "luns(): Target 'no-such-target' is not available"));
     ok(Dumper($SCST->luns('scst_local', 'local1')),
        Dumper({ '0' => 'disk01', '1' => 'disk02', '2' => 'disk01',
-		'3' => 'disk02' }));
+		'3' => 'disk02' }, undef));
     ok(Dumper($SCST->luns('scst_local', 'local1', 'group1')),
        Dumper({ '0' => 'disk01', '2' => 'disk02', '4' => 'disk01',
-		'6' => 'disk02' }));
+		'6' => 'disk02' }, undef));
 
     ok(lunReadOnly($SCST, 'scst_local', 'local1', 0), '0');
     ok($SCST->setLunAttribute(), $SCST->SCST_C_LUN_SETATTR_FAIL);
@@ -293,11 +302,11 @@ sub lunTest {
     ok($SCST->replaceLun('scst_local', 'local1', 0, 'disk02', {}), 0);
     ok(Dumper($SCST->luns('scst_local', 'local1')),
        Dumper({ '0' => 'disk02', '1' => 'disk02', '2' => 'disk01',
-		'3' => 'disk02' }));
+		'3' => 'disk02' }, undef));
     ok($SCST->replaceLun('scst_local', 'local1', 0, 'disk01', {}), 0);
     ok(Dumper($SCST->luns('scst_local', 'local1')),
        Dumper({ '0' => 'disk01', '1' => 'disk02', '2' => 'disk01',
-		'3' => 'disk02' }));
+		'3' => 'disk02' }, undef));
 
     ok($SCST->clearLuns(undef, undef), $SCST->SCST_C_TGT_CLR_LUN_FAIL);
     ok($SCST->clearLuns(undef, undef, 'group1'),
@@ -313,15 +322,16 @@ sub lunTest {
     ok($SCST->removeLun('scst_local', 'local1', '8', 'group1'),
        $SCST->SCST_C_GRP_NO_LUN);
     ok($SCST->clearLuns('scst_local', 'local1'), 0);
-    ok(Dumper($SCST->luns('scst_local', 'local1')), Dumper({ }));
+    ok(Dumper($SCST->luns('scst_local', 'local1')), Dumper({ }, undef));
     ok(Dumper($SCST->luns('scst_local', 'local1', 'group1')),
        Dumper({ '0' => 'disk01', '2' => 'disk02', '4' => 'disk01',
-		'6' => 'disk02' }));
+		'6' => 'disk02' }, undef));
     ok($SCST->removeLun('scst_local', 'local1', '4', 'group1'), 0);
     ok(Dumper($SCST->luns('scst_local', 'local1', 'group1')),
-       Dumper({ '0' => 'disk01', '2' => 'disk02', '6' => 'disk02' }));
+       Dumper({ '0' => 'disk01', '2' => 'disk02', '6' => 'disk02' }, undef));
     ok($SCST->clearLuns('scst_local', 'local1', 'group1'), 0);
-    ok(Dumper($SCST->luns('scst_local', 'local1', 'group1')), Dumper({ }));
+    ok(Dumper($SCST->luns('scst_local', 'local1', 'group1')),
+       Dumper({ }, undef));
 
     ok($SCST->removeInitiator('scst_local', 'local1', 'group1', 'ini1'), 0);
     ok($SCST->removeGroup('scst_local', 'local1', 'group1'), 0);
@@ -339,7 +349,7 @@ sub remTargets {
 
     ok($SCST->removeVirtualTarget('scst_local', 'local2'), 0);
     ok($SCST->removeVirtualTarget('scst_local', 'local1'), 0);
-    ok(Dumper($SCST->targets('scst_local')), Dumper([]));
+    ok(Dumper($SCST->targets('scst_local')), Dumper([], undef));
 }
 
 my $_DEBUG_ = 0;
diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/04-alua.t b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/04-alua.t
index be0ffcbde..c2b39a7d1 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/04-alua.t
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/04-alua.t
@@ -4,7 +4,7 @@ use strict;
 use Test;
 
 BEGIN {
-    plan tests => 65;
+    plan tests => 62;
 }
 
 use Data::Dumper;
@@ -13,7 +13,8 @@ use SCST::SCST;
 sub setup {
     my $SCST = shift;
 
-    my %drivers = map { $_ => 1 } @{$SCST->drivers()};
+    my ($drivers, $errorString) = $SCST->drivers();
+    my %drivers = map { $_ => 1 } @{$drivers};
     ok(exists($drivers{'iscsi'}));
     ok(exists($drivers{'scst_local'}));
 
@@ -37,17 +38,18 @@ sub setup {
 sub test {
     my $SCST = shift;
 
-    ok(Dumper($SCST->deviceGroups()), Dumper([]));
+    ok(Dumper($SCST->deviceGroups()), Dumper([], undef));
 
     ok($SCST->addDeviceGroup('dg1'), 0);
     ok($SCST->addDeviceGroup('dg2'), 0);
     ok($SCST->addDeviceGroup('dg3'), 0);
     ok($SCST->addDeviceGroup('dg4'), 0);
 
-    ok(Dumper($SCST->deviceGroups()), Dumper(['dg1', 'dg2', 'dg3', 'dg4']));
+    ok(Dumper($SCST->deviceGroups()),
+       Dumper(['dg1', 'dg2', 'dg3', 'dg4'], undef));
 
-    ok(Dumper($SCST->deviceGroupDevices()), Dumper(undef));
-    ok(Dumper($SCST->deviceGroupDevices('dg1')), Dumper([]));
+    ok(Dumper($SCST->deviceGroupDevices()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->deviceGroupDevices('dg1')), Dumper([], undef));
     ok($SCST->addDeviceGroupDevice('dg1', 'disk01'), 0);
     ok($SCST->addDeviceGroupDevice('dg1', 'disk01'),
        $SCST->SCST_C_DGRP_DEVICE_EXISTS);
@@ -56,26 +58,28 @@ sub test {
        $SCST->SCST_C_DGRP_DEVICE_OTHER);
     ok($SCST->addDeviceGroupDevice('dg3', 'disk03'), 0);
     ok($SCST->addDeviceGroupDevice('dg4', 'disk04'), 0);
-    ok(Dumper($SCST->deviceGroupDevices('dg1')), Dumper(['disk01']));
-    ok(Dumper($SCST->deviceGroupDevices('dg2')), Dumper(['disk02']));
-    ok(Dumper($SCST->deviceGroupDevices('dg3')), Dumper(['disk03']));
-    ok(Dumper($SCST->deviceGroupDevices('dg4')), Dumper(['disk04']));
+    ok(Dumper($SCST->deviceGroupDevices('dg1')), Dumper(['disk01'], undef));
+    ok(Dumper($SCST->deviceGroupDevices('dg2')), Dumper(['disk02'], undef));
+    ok(Dumper($SCST->deviceGroupDevices('dg3')), Dumper(['disk03'], undef));
+    ok(Dumper($SCST->deviceGroupDevices('dg4')), Dumper(['disk04'], undef));
 
-    ok($SCST->targetGroups(), undef);
-    ok($SCST->targetGroups('no-such-device-group'), undef);
-    ok($SCST->{'err_string'},
-       "targetGroups(): Device group 'no-such-device-group' does not exist");
-    ok(Dumper($SCST->targetGroups('dg1')), Dumper([]));
+    ok(Dumper($SCST->targetGroups()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targetGroups('no-such-device-group')),
+       Dumper(undef, "targetGroups(): Device group 'no-such-device-group'" .
+	      " does not exist"));
+    ok(Dumper($SCST->targetGroups('dg1')), Dumper([], undef));
 
-    ok($SCST->targetGroupTargets(), undef);
-    ok($SCST->targetGroupTargets('no-such-device-group'), undef);
-    ok($SCST->targetGroupTargets('no-such-device-group', 'tg1'), undef);
-    ok($SCST->{'err_string'},
-       "targetGroupTargets(): Device group 'no-such-device-group' does not exist");
-    ok($SCST->targetGroupTargets('dg1', 'no-such-target-group'), undef);
-    ok($SCST->{'err_string'},
-       "targetGroupTargets(): Target group 'no-such-target-group' does not exist");
-    ok($SCST->targetGroupTargets('dg1', 'tg1'), undef);
+    ok(Dumper($SCST->targetGroupTargets()), Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targetGroupTargets('no-such-device-group')),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targetGroupTargets('no-such-device-group', 'tg1')),
+       Dumper(undef, "targetGroupTargets(): Device group 'no-such-device-".
+	      "group' does not exist"));
+    ok(Dumper($SCST->targetGroupTargets('dg1', 'no-such-target-group')),
+       Dumper(undef, "targetGroupTargets(): Target group 'no-such-target-".
+	      "group' does not exist"));
+    ok(Dumper($SCST->targetGroupTargets('dg1', 'tg1')), Dumper(undef,
+	      "targetGroupTargets(): Target group 'tg1' does not exist"));
     ok($SCST->addTargetGroup(), $SCST->SCST_C_DGRP_ADD_GRP_FAIL);
     ok($SCST->addTargetGroup('no-such-device-group', 'tg1'),
        $SCST->SCST_C_DEV_GRP_NO_GROUP);
@@ -83,13 +87,13 @@ sub test {
     ok($SCST->addTargetGroup('dg1', 'tg1'), $SCST->SCST_C_DGRP_GROUP_EXISTS);
     ok($SCST->addTargetGroup('dg1', 'tg2'), 0);
 
-    ok(Dumper($SCST->targetGroupAttributes('dg1', 'tg1')->{'group_id'}),
-	      Dumper({ 'keys' => { '0' => { 'value' => '0' } },
-		       'static' => 0 }));
+    my ($tga, $errorString) = $SCST->targetGroupAttributes('dg1', 'tg1');
+    ok(Dumper($tga->{'group_id'}),
+       Dumper({ 'keys' => { '0' => { 'value' => '0' } }, 'static' => 0 }));
     ok($SCST->setTargetGroupAttribute('dg1', 'tg1', 'group_id', 7), 0);
-    ok(Dumper($SCST->targetGroupAttributes('dg1', 'tg1')->{'group_id'}),
-	      Dumper({ 'keys' => { '0' => { 'value' => '7' } },
-		       'static' => 0 }));
+    ($tga, $errorString) = $SCST->targetGroupAttributes('dg1', 'tg1');
+    ok(Dumper($tga->{'group_id'}),
+       Dumper({ 'keys' => { '0' => { 'value' => '7' } }, 'static' => 0 }));
 
     ok($SCST->addTargetGroupTarget(), $SCST->SCST_C_TGRP_ADD_TGT_FAIL);
     ok($SCST->addTargetGroupTarget('no-such-device-group', 'tg1', 'tgt1'),
@@ -101,23 +105,24 @@ sub test {
        $SCST->SCST_C_TGRP_TGT_EXISTS);
     ok($SCST->addTargetGroupTarget('dg1', 'tg2', 'tgt2'), 0);
 
-    ok(Dumper($SCST->targetGroupTargetAttributes('dg1', 'tg1', 'tgt1')
-	      ->{'rel_tgt_id'}),
-	      Dumper({ 'keys' => { '0' => { 'value' => '0' } },
-		       'static' => 0 }));
+    my $tgta;
+    ($tgta, $errorString) =
+	$SCST->targetGroupTargetAttributes('dg1', 'tg1', 'tgt1');
+    ok(Dumper($tgta->{'rel_tgt_id'}),
+       Dumper({ 'keys' => { '0' => { 'value' => '0' } }, 'static' => 0 }));
     ok($SCST->setTargetGroupTargetAttribute('dg1', 'tg1', 'tgt1', 'rel_tgt_id',
 					    8), 0);
-    ok(Dumper($SCST->targetGroupTargetAttributes('dg1', 'tg1', 'tgt1')
-	      ->{'rel_tgt_id'}),
-	      Dumper({ 'keys' => { '0' => { 'value' => '8' } },
-		       'static' => 0 }));
+    ($tgta, $errorString) =
+	$SCST->targetGroupTargetAttributes('dg1', 'tg1', 'tgt1');
+    ok(Dumper($tgta->{'rel_tgt_id'}),
+       Dumper({ 'keys' => { '0' => { 'value' => '8' } }, 'static' => 0 }));
 
     ok($SCST->removeDeviceGroup('dg1'), 0);
     ok($SCST->removeDeviceGroup('dg2'), 0);
     ok($SCST->removeDeviceGroup('dg3'), 0);
     ok($SCST->removeDeviceGroup('dg4'), 0);
 
-    ok(Dumper($SCST->deviceGroups()), Dumper([]));
+    ok(Dumper($SCST->deviceGroups()), Dumper([], undef));
 }
 
 sub teardown {
diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/05-dynattr.t b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/05-dynattr.t
index 47592e516..02ff569ca 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/05-dynattr.t
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/05-dynattr.t
@@ -4,7 +4,7 @@ use strict;
 use Test;
 
 BEGIN {
-    plan tests => 57;
+    plan tests => 55;
 }
 
 use Data::Dumper;
@@ -13,7 +13,8 @@ use SCST::SCST;
 sub setup {
     my $SCST = shift;
 
-    my %drivers = map { $_ => 1 } @{$SCST->drivers()};
+    my ($drivers, $errorString) = $SCST->drivers();
+    my %drivers = map { $_ => 1 } @{$drivers};
     ok(exists($drivers{'iscsi'}));
     ok(exists($drivers{'scst_local'}));
 
@@ -28,13 +29,14 @@ sub setup {
 sub testDriverDynAttr {
     my $SCST = shift;
 
-    ok($SCST->driverDynamicAttributes(), undef);
-    ok($SCST->driverDynamicAttributes('no-such-driver'), undef);
-    ok($SCST->{'err_string'},
-       "driverDynamicAttributes(): Driver 'no-such-driver' is not available");
-    ok(Dumper($SCST->driverDynamicAttributes('scst_local')), Dumper({}));
+    ok(Dumper($SCST->driverDynamicAttributes()),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->driverDynamicAttributes('no-such-driver')),
+       Dumper(undef, "driverDynamicAttributes(): Driver 'no-such-driver' is " .
+	      "not available"));
+    ok(Dumper($SCST->driverDynamicAttributes('scst_local')), Dumper({}, undef));
     ok(Dumper($SCST->driverDynamicAttributes('iscsi')),
-       Dumper({ 'IncomingUser' => '', 'OutgoingUser' => '' }));
+       Dumper({ 'IncomingUser' => '', 'OutgoingUser' => '' }, undef));
     ok($SCST->checkDriverDynamicAttributes('no-such-driver'),
        $SCST->SCST_C_DRV_NO_DRIVER);
     ok($SCST->checkDriverDynamicAttributes('no-such-driver', { }),
@@ -60,7 +62,8 @@ sub testDriverDynAttr {
 					'bar 12CharSecret'), 0);
     ok($SCST->addDriverDynamicAttribute('iscsi', 'IncomingUser',
 					'joe 12charsecret'), 0);
-    ok(Dumper($SCST->driverAttributes('iscsi')->{'IncomingUser'}),
+    my ($da, $errorString) = $SCST->driverAttributes('iscsi');
+    ok(Dumper($da->{'IncomingUser'}),
        Dumper({ 'keys' => { '0' => { 'value' => 'bar 12CharSecret' },
 	                    '1' => { 'value' => 'joe 12charsecret' } },
 	        'static' => 0 }));
@@ -73,21 +76,23 @@ sub testDriverDynAttr {
 					   'joe 12charsecret'), 0);
     ok($SCST->removeDriverDynamicAttribute('iscsi', 'IncomingUser',
 					   'bar 12CharSecret'), 0);
-    ok(!exists($SCST->driverAttributes('iscsi')->{'IncomingUser'}));
+    ($da, $errorString) = $SCST->driverAttributes('iscsi');
+    ok(!exists($da->{'IncomingUser'}));
 }
 
 sub testTargetDynAttr {
     my $SCST = shift;
 
-    ok($SCST->targetDynamicAttributes(), undef);
-    ok($SCST->targetDynamicAttributes('no-such-driver'), undef);
-    ok($SCST->{'err_string'},
-       "targetDynamicAttributes(): Driver 'no-such-driver' is not available");
-    ok(Dumper($SCST->targetDynamicAttributes('scst_local')), Dumper({}));
+    ok(Dumper($SCST->targetDynamicAttributes()),
+       Dumper(undef, "Too few arguments"));
+    ok(Dumper($SCST->targetDynamicAttributes('no-such-driver')),
+       Dumper(undef, "targetDynamicAttributes(): Driver 'no-such-driver' is" .
+	      " not available"));
+    ok(Dumper($SCST->targetDynamicAttributes('scst_local')), Dumper({}, undef));
     ok(Dumper($SCST->targetDynamicAttributes('iscsi')),
        Dumper({ 'IncomingUser' => '',
 		'OutgoingUser' => '',
-		'allowed_portal' => '' }));
+		'allowed_portal' => '' }, undef));
     ok($SCST->checkTargetDynamicAttributes('no-such-driver'),
        $SCST->SCST_C_DRV_NO_DRIVER);
     ok($SCST->checkTargetDynamicAttributes('no-such-driver', { }),
@@ -116,7 +121,8 @@ sub testTargetDynAttr {
 					'bar 12CharSecret'), 0);
     ok($SCST->addTargetDynamicAttribute('iscsi', 'tgt1', 'IncomingUser',
 					'joe 12charsecret'), 0);
-    ok(Dumper($SCST->targetAttributes('iscsi', 'tgt1')->{'IncomingUser'}),
+    my ($ta, $errorString) = $SCST->targetAttributes('iscsi', 'tgt1');
+    ok(Dumper($ta->{'IncomingUser'}),
        Dumper({ 'keys' => { '0' => { 'value' => 'bar 12CharSecret' },
 	                    '1' => { 'value' => 'joe 12charsecret' } },
 	        'static' => 0 }));
@@ -132,7 +138,8 @@ sub testTargetDynAttr {
 					   'joe 12charsecret'), 0);
     ok($SCST->removeTargetDynamicAttribute('iscsi', 'tgt1', 'IncomingUser',
 					   'bar 12CharSecret'), 0);
-    ok(!exists($SCST->targetAttributes('iscsi', 'tgt1')->{'IncomingUser'}));
+    ($ta, $errorString) = $SCST->targetAttributes('iscsi', 'tgt1');
+    ok(!exists($ta->{'IncomingUser'}));
 }
 
 sub teardown {
diff --git a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/06-cont-on-err.t b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/06-cont-on-err.t
index 411be7a4e..2aa100c6a 100644
--- a/scstadmin/scstadmin.sysfs/scst-0.9.10/t/06-cont-on-err.t
+++ b/scstadmin/scstadmin.sysfs/scst-0.9.10/t/06-cont-on-err.t
@@ -29,7 +29,8 @@ use File::Temp qw/tempfile/;
 sub setup {
     my $SCST = shift;
 
-    my %drivers = map { $_ => 1 } @{$SCST->drivers()};
+    my ($drivers, $errorString) = $SCST->drivers();
+    my %drivers = map { $_ => 1 } @{$drivers};
     ok(exists($drivers{'ib_srpt'}));
 }
 
diff --git a/scstadmin/scstadmin.sysfs/scstadmin b/scstadmin/scstadmin.sysfs/scstadmin
index 334fb8750..6e976e93b 100755
--- a/scstadmin/scstadmin.sysfs/scstadmin
+++ b/scstadmin/scstadmin.sysfs/scstadmin
@@ -1170,58 +1170,58 @@ sub readWorkingConfig {
 
 	# Get current handlers/devices
 
-	my $handlers = $SCST->handlers();
-	immediateExit($SCST->errorString());
+	my ($handlers, $errorString) = $SCST->handlers();
+	immediateExit($errorString);
 
 	foreach my $handler (@{$handlers}) {
-		my $devices = $SCST->devicesByHandler($handler);
-		immediateExit($SCST->errorString());
+		my ($devices, $errorString) = $SCST->devicesByHandler($handler);
+		immediateExit($errorString);
 		$CURRENT{'handler'}->{$handler} = $devices;
 	}
 
 	# Get current assignments
 
-	my $drivers = $SCST->drivers();
-	immediateExit($SCST->errorString());
+	my ($drivers, $errorString) = $SCST->drivers();
+	immediateExit($errorString);
 
 	foreach my $driver (@{$drivers}) {
 		my %empty;
 		$CURRENT{'assign'}->{$driver} = \%empty;
-		my $targets = $SCST->targets($driver);
-		immediateExit($SCST->errorString());
+		my ($targets, $errorString) = $SCST->targets($driver);
+		immediateExit($errorString);
 		foreach my $target (@{$targets}) {
 			my %empty;
 			$CURRENT{'assign'}->{$driver}->{$target} = \%empty;
 
-			my $luns = $SCST->luns($driver, $target);
+			my ($luns, $errorString) = $SCST->luns($driver, $target);
 
 			$CURRENT{'assign'}->{$driver}->{$target}->{'LUN'} = $luns if (defined($luns));
 
-			my $groups = $SCST->groups($driver, $target);
-			immediateExit($SCST->errorString());
+			my ($groups, $errorString) = $SCST->groups($driver, $target);
+			immediateExit($errorString);
 			foreach my $group (@{$groups}) {
-				$CURRENT{'assign'}->{$driver}->{$target}->{'GROUP'}->{$group}->{'INITIATORS'} =
-				  $SCST->initiators($driver, $target, $group);
-				immediateExit($SCST->errorString());
-
-				$CURRENT{'assign'}->{$driver}->{$target}->{'GROUP'}->{$group}->{'LUN'} =
-				  $SCST->luns($driver, $target, $group);
-				immediateExit($SCST->errorString());
+				my ($initiators, $errorString) = $SCST->initiators($driver, $target, $group);
+				immediateExit($errorString);
+				$CURRENT{'assign'}->{$driver}->{$target}->{'GROUP'}->{$group}->{'INITIATORS'} = $initiators;
+				my ($luns, $errorString) = $SCST->luns($driver, $target, $group);
+				$CURRENT{'assign'}->{$driver}->{$target}->{'GROUP'}->{$group}->{'LUN'} = $luns;
+				immediateExit($errorString);
 			}
 		}
 	}
 
-	my $dgroups = $SCST->deviceGroups();
-	immediateExit($SCST->errorString());
+	my ($dgroups, $errorString) = $SCST->deviceGroups();
+	immediateExit($errorString);
 
 	foreach my $dgroup (@{$dgroups}) {
-		$CURRENT{'dgroups'}->{$dgroup}->{'devices'} = $SCST->deviceGroupDevices($dgroup);
-		immediateExit($SCST->errorString());			
-		my $tgroups = $SCST->targetGroups($dgroup);
-		immediateExit($SCST->errorString());
+		my ($dgd, $errorString) = $SCST->deviceGroupDevices($dgroup);
+		immediateExit($errorString);			
+		$CURRENT{'dgroups'}->{$dgroup}->{'devices'} = $dgd;
+		my ($tgroups, $errorString) = $SCST->targetGroups($dgroup);
+		immediateExit($errorString);
 		foreach my $tgroup (@{$tgroups}) {
-			$CURRENT{'dgroups'}->{$dgroup}->{'tgroups'}->{$tgroup}->{'targets'} =
-			  $SCST->targetGroupTargets($dgroup, $tgroup);
+			my ($tgt, $errorString) = $SCST->targetGroupTargets($dgroup, $tgroup);
+			$CURRENT{'dgroups'}->{$dgroup}->{'tgroups'}->{$tgroup}->{'targets'} = $tgt;
 		}
 	}
 
@@ -1348,8 +1348,8 @@ sub writeConfiguration {
 	print $io "# Automatically generated by $Version.\n\n";
 
 	{
-		my $attributes = $SCST->scstAttributes();
-		immediateExit($SCST->errorString());
+		my ($attributes, $errorString) = $SCST->scstAttributes();
+		immediateExit($errorString);
 
 		print $io serializeKeyAttr("", $attributes);
 		if ($nonkey) {
@@ -1366,8 +1366,8 @@ sub writeConfiguration {
 		my $handler_buff;
 		my $handler_buff_nk;
 
-		my $handler_attrs = $SCST->deviceCreateAttributes($handler);
-		my $attributes = $SCST->handlerAttributes($handler);
+		my ($handler_attrs, $errorString) = $SCST->deviceCreateAttributes($handler);
+		my ($attributes, $errorString) = $SCST->handlerAttributes($handler);
 
 		$handler_buff = serializeKeyAttr("\t", $attributes);
 		$handler_buff_nk = serializeNkAttr("\t", $attributes) if ($nonkey);
@@ -1378,7 +1378,7 @@ sub writeConfiguration {
 		foreach my $device (sort @{$devices}) {
 			$device_buff .= "\tDEVICE $device";
 
-			my $attributes = $SCST->deviceAttributes($device);
+			my ($attributes, $errorString) = $SCST->deviceAttributes($device);
 
 			my $attribute_buff;
 			my $attribute_buff_nk;
@@ -1423,7 +1423,7 @@ sub writeConfiguration {
 	foreach my $driver (sort keys %{$CURRENT{'assign'}}) {
 		my $driver_buff;
 
-		my $drv_attrs = $SCST->driverAttributes($driver);
+		my ($drv_attrs, $errorString) = $SCST->driverAttributes($driver);
 
 		my $drv_attr_buff;
 		my $drv_attr_buff_nk;
@@ -1434,13 +1434,13 @@ sub writeConfiguration {
 		$drv_attr_buff_nk .= "\n" if ($drv_attr_buff_nk);
 
 		my $targets = $CURRENT{'assign'}->{$driver};
-		my $tgt_attrs = $SCST->targetCreateAttributes($driver);
+		my ($tgt_attrs, $errorString) = $SCST->targetCreateAttributes($driver);
 
 		my $target_buff;
 		foreach my $target (sort keys %{$targets}) {
 			$target_buff .= "\tTARGET $target";
 
-			my $attributes = $SCST->targetAttributes($driver, $target);
+			my ($attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
 			my $attribute_buff;
 			my $attribute_buff_nk;
@@ -1456,7 +1456,7 @@ sub writeConfiguration {
 			$attribute_buff_nk .= "\n" if ($attribute_buff_nk);
 
 			my $luns = $CURRENT{'assign'}->{$driver}->{$target}->{'LUN'};
-			my $lun_attrs = $SCST->lunCreateAttributes($driver, $target);
+			my ($lun_attrs, $errorString) = $SCST->lunCreateAttributes($driver, $target);
 
 			my $t_lun_buff;
 			foreach my $lun (sort numerically keys %{$luns}) {
@@ -1464,7 +1464,7 @@ sub writeConfiguration {
 
 				$t_lun_buff .= "\t\tLUN $lun $lun_dev";
 
-				my $attributes = $SCST->lunAttributes($driver, $target, $lun);
+				my ($attributes, $errorString) = $SCST->lunAttributes($driver, $target, $lun);
 				my $l_attribute_buff =
 				    serializeKeyAttr("\t\t\t",
 						     $attributes,
@@ -1495,8 +1495,8 @@ sub writeConfiguration {
 
 			my $group_buff;
 			foreach my $group (sort keys %{$groups}) {
-				my $lun_attrs = $SCST->lunCreateAttributes($driver, $target, $group);
-				my $ini_attrs = $SCST->initiatorCreateAttributes($driver, $target, $group);
+				my ($lun_attrs, $errorString) = $SCST->lunCreateAttributes($driver, $target, $group);
+				my ($ini_attrs, $errorString) = $SCST->initiatorCreateAttributes($driver, $target, $group);
 
 				$group_buff .= "\t\tGROUP $group";
 
@@ -1508,7 +1508,7 @@ sub writeConfiguration {
 
 					$lun_buff .= "\t\t\tLUN $lun $lun_dev";
 
-					my $attributes = $SCST->lunAttributes($driver, $target, $lun, $group);
+					my ($attributes, $errorString) = $SCST->lunAttributes($driver, $target, $lun, $group);
 
 					my $l_attribute_buff
 					    = serializeKeyAttr("\t\t\t\t",
@@ -1540,7 +1540,7 @@ sub writeConfiguration {
 				foreach my $init (sort @{$inits}) {
 					$init_buff .= "\n\t\t\tINITIATOR " . escapeMeta($init);
 
-					my $attributes = $SCST->initiatorAttributes($driver, $target, $group, $init);
+					my ($attributes, $errorString) = $SCST->initiatorAttributes($driver, $target, $group, $init);
 
 					my $i_attribute_buff
 					    = serializeKeyAttr("\t\t\t\t",
@@ -1572,7 +1572,7 @@ sub writeConfiguration {
 					$group_buff .= $init_buff;
 				}
 
-				my $grp_attributes = $SCST->groupAttributes($driver, $target, $group);
+				my ($grp_attributes, $errorString) = $SCST->groupAttributes($driver, $target, $group);
 				my $g_attribute_buff
 				    = serializeKeyAttr("\t\t\t",
 						       $grp_attributes);
@@ -1636,7 +1636,7 @@ sub writeConfiguration {
 		}
 	}
 
-	my $dga = $SCST->aluaAttributes();
+	my ($dga, $errorString) = $SCST->aluaAttributes();
 	my $dga_buff = serializeKeyAttr("\t", $dga);
 	my $dga_buff_nk = serializeNkAttr("\t", $dga) if ($nonkey);
 	if ($dga_buff_nk) {
@@ -1652,7 +1652,7 @@ sub writeConfiguration {
 	foreach my $dgroup (sort keys %{$CURRENT{'dgroups'}}) {
 		my $dgroup_buff;
 
-		my $dgroup_attrs = $SCST->deviceGroupAttributes($dgroup);
+		my ($dgroup_attrs, $errorString) = $SCST->deviceGroupAttributes($dgroup);
 
 		my $dgrp_attr_buff;
 		my $dgrp_attr_buff_nk;
@@ -1679,7 +1679,7 @@ sub writeConfiguration {
 		foreach my $tgroup (sort keys %{$tgroups}) {
 			$tgroup_buff .= "\tTARGET_GROUP $tgroup";
 
-			my $attributes = $SCST->targetGroupAttributes($dgroup, $tgroup);
+			my ($attributes, $errorString) = $SCST->targetGroupAttributes($dgroup, $tgroup);
 
 			my $attribute_buff;
 			my $attribute_buff_nk;
@@ -1695,7 +1695,7 @@ sub writeConfiguration {
 			foreach my $tgt (@{$tgts}) {
 				$tgt_buff .= "\t\tTARGET $tgt";
 
-				my $tgt_attrs = $SCST->targetGroupTargetAttributes($dgroup, $tgroup, $tgt);
+				my ($tgt_attrs, $errorString) = $SCST->targetGroupTargetAttributes($dgroup, $tgroup, $tgt);
 
 				my $t_attribute_buff
 				  = serializeKeyAttr("\t\t\t", $tgt_attrs);
@@ -1993,7 +1993,7 @@ sub applyConfigDevices {
 	foreach my $handler (keys %{$handlers}) {
 		foreach my $device (@{$$handlers{$handler}}) {
 			if (!defined($$config{'HANDLER'}->{$handler}->{'DEVICE'}->{$device})) {
-				my $attributes = $SCST->deviceAttributes($device);
+				my ($attributes, $errorString) = $SCST->deviceAttributes($device);
 
 				if ($deletions) {
 					closeDevice($handler, $device, $deletions);
@@ -2020,14 +2020,14 @@ sub applyConfigDevices {
 
 				my $attributes = configToAttr(\%_attributes);
 				my $create_attrs = configToAttr(\%_attributes);
-				my $possible = $SCST->deviceCreateAttributes($handler);
-				condExit($SCST->errorString());
+				my ($possible, $errorString) = $SCST->deviceCreateAttributes($handler);
+				condExit($errorString);
 				filterCreateAttributes($possible, $create_attrs, FALSE);
 				filterCreateAttributes($possible, $attributes, TRUE);
 
 				if (handlerHasDevice($handler, $device)) {
-					my $old_create_attrs = $SCST->deviceAttributes($device);
-					condExit($SCST->errorString());
+					my ($old_create_attrs, $errorString) = $SCST->deviceAttributes($device);
+					condExit($errorString);
 					filterCreateAttributes($possible, $old_create_attrs, FALSE);
 
 					if (compareToKeyAttribute($create_attrs, $old_create_attrs)) {
@@ -2106,10 +2106,10 @@ sub applyConfigAssignments {
 					}
 				} else {
 					my $c_attrs = configToAttr($$config{'TARGET_DRIVER'}->{$driver}->{'TARGET'}->{$target}->{'LUN'}->{$lun}->{$device});
-					my $o_attrs = $SCST->lunAttributes($driver, $target, $lun);
-					condExit($SCST->errorString());
-					my $possible = $SCST->lunCreateAttributes($driver, $target);
-					condExit($SCST->errorString());
+					my ($o_attrs, $errorString) = $SCST->lunAttributes($driver, $target, $lun);
+					condExit($errorString);
+					my ($possible, $errorString) = $SCST->lunCreateAttributes($driver, $target);
+					condExit($errorString);
 
 					filterCreateAttributes($possible, $c_attrs, FALSE);
 
@@ -2149,10 +2149,10 @@ sub applyConfigAssignments {
 						}
 					} else {
 						my $c_attrs = configToAttr($$config{'TARGET_DRIVER'}->{$driver}->{'TARGET'}->{$target}->{'GROUP'}->{$group}->{'LUN'}->{$lun}->{$device});
-						my $o_attrs = $SCST->lunAttributes($driver, $target, $lun, $group);
-						condExit($SCST->errorString());
-						my $possible = $SCST->lunCreateAttributes($driver, $target, $group);
-						condExit($SCST->errorString());
+						my ($o_attrs, $errorString) = $SCST->lunAttributes($driver, $target, $lun, $group);
+						condExit($errorString);
+						my ($possible, $errorString) = $SCST->lunCreateAttributes($driver, $target, $group);
+						condExit($errorString);
 
 						filterCreateAttributes($possible, $c_attrs, FALSE);
 
@@ -2233,7 +2233,7 @@ sub applyConfigEnableDrivers {
 		}
 
 		my $attributes = configToAttr(\%_attributes);
-		my $d_attributes = $SCST->driverAttributes($driver);
+		my ($d_attributes, $errorString) = $SCST->driverAttributes($driver);
 
 		if (defined($$d_attributes{'enabled'}) &&
 		    ($$d_attributes{'enabled'}->{'value'} != $$attributes{'enabled'})) {
@@ -2474,10 +2474,10 @@ sub applyTargetAssignments {
 
 	my $possible;
 
-	my $is_virtual = $SCST->driverIsVirtualCapable($driver);
+	my ($is_virtual, $errorString) = $SCST->driverIsVirtualCapable($driver);
 
 	if ($is_virtual) {
-		$possible = $SCST->targetCreateAttributes($driver);
+		($possible, $errorString) = $SCST->targetCreateAttributes($driver);
 	}
 
 	foreach my $target (sort keys %{$targets}) {
@@ -2554,7 +2554,7 @@ sub applyConfigEnableTargets {
 				}
 
 				my $attributes = configToAttr(\%_attributes);
-				my $t_attributes = $SCST->targetAttributes($driver, $target);
+				my ($t_attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
 				if (defined($$t_attributes{'enabled'}) &&
 				    ($$t_attributes{'enabled'}->{'value'} != $$attributes{'enabled'})) {
@@ -2713,17 +2713,17 @@ sub clearConfiguration {
 
 	foreach my $handler (sort keys %{$handlers}) {
 		foreach my $device (@{$$handlers{$handler}}) {
-			my $attributes = $SCST->deviceAttributes($device);
+			my ($attributes, $errorString) = $SCST->deviceAttributes($device);
 			closeDevice($handler, $device, TRUE);
 		}
 	}
 
 	# Todo - check return code
 
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 
 	foreach my $driver (@{$drivers}) {
-		my $targets = $SCST->targets($driver);
+		my ($targets, $errorString) = $SCST->targets($driver);
 
 		foreach my $target (@{$targets}) {
 			disableTarget($driver, $target);
@@ -2743,10 +2743,10 @@ sub addVirtualTarget {
 	my $attributes = shift;
 
 	# Enable all hardware targets before creating virtual ones
-	my $targets = $SCST->targets($driver);
+	my ($targets, $errorString) = $SCST->targets($driver);
 
 	foreach my $_target (@{$targets}) {
-		my $attributes = $SCST->targetAttributes($driver, $_target);
+		my ($attributes, $errorString) = $SCST->targetAttributes($driver, $_target);
 
 		if (defined($$attributes{'hw_target'}) &&
 		    !$$attributes{'enabled'}->{'value'}) {
@@ -2779,7 +2779,7 @@ sub listHandlers {
 
 	return listHandler($handler) if ($handler);
 
-	my $handlers = $SCST->handlers();
+	my ($handlers, $errorString) = $SCST->handlers();
 
 	my $l_handler;
 	foreach my $handler (@{$handlers}) {
@@ -2805,7 +2805,7 @@ sub listHandler {
 	my %toprint;
 
 	my $got_handler = ($handler ne '');
-	my $handlers = $SCST->handlers();
+	my ($handlers, $errorString) = $SCST->handlers();
 
 	my $l_device;
 	my $l_handler;
@@ -2818,7 +2818,7 @@ sub listHandler {
 
 			$l_handler = length($handler) if ($l_handler < length($handler));
 
-			my $devices = $SCST->devicesByHandler($handler);
+			my ($devices, $errorString) = $SCST->devicesByHandler($handler);
 
 			if ($#{$devices} == -1) {
 				push @{$devices}, '-';
@@ -2839,7 +2839,7 @@ sub listHandler {
 		print "\n";
 
 		foreach my $handler (keys %toprint) {
-			my $devices = $SCST->devicesByHandler($handler);
+			my ($devices, $errorString) = $SCST->devicesByHandler($handler);
 			my $first = TRUE;
 
 			if ($#{$devices} == -1) {
@@ -2874,9 +2874,9 @@ sub listDevice {
 	my $device = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->deviceAttributes($device);
+	my ($attributes, $errorString) = $SCST->deviceAttributes($device);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such device '$device' exists.\n";
@@ -2892,7 +2892,7 @@ sub listDeviceGroups {
 
 	return listDeviceGroup($group) if ($group ne '');
 
-	my $groups = $SCST->deviceGroups();
+	my ($groups, $errorString) = $SCST->deviceGroups();
 
 	my $l_group;
 	foreach my $group (@{$groups}) {
@@ -2919,7 +2919,7 @@ sub listDeviceGroups {
 sub listDeviceGroup {
 	my $group = shift;
 
-	my $devices = $SCST->deviceGroupDevices($group);
+	my ($devices, $errorString) = $SCST->deviceGroupDevices($group);
 
 	my $l_device;
 	foreach my $device (@{$devices}) {
@@ -2939,7 +2939,7 @@ sub listDeviceGroup {
 		print "\t$device\n";
 	}
 
-	my $tgroups = $SCST->targetGroups($group);
+	my ($tgroups, $errorString) = $SCST->targetGroups($group);
 
 	my $l_tgroup;
 	foreach my $tgroup (@{$tgroups}) {
@@ -2970,7 +2970,7 @@ sub listTargetGroups {
 	return listDeviceGroups(undef, TRUE) if ($group eq '');
 	return listTargetGroup($group, $tgroup) if ($tgroup ne '');
 
-	my $tgroups = $SCST->targetGroups($group);
+	my ($tgroups, $errorString) = $SCST->targetGroups($group);
 
 	my $l_tgroup;
 	foreach my $tgroup (@{$tgroups}) {
@@ -3001,7 +3001,7 @@ sub listTargetGroup {
 	my $group = shift;
 	my $tgroup = shift;
 
-	my $targets = $SCST->targetGroupTargets($group, $tgroup);
+	my ($targets, $errorString) = $SCST->targetGroupTargets($group, $tgroup);
 
 	my $l_tgt;
 	foreach my $tgt (@{$targets}) {
@@ -3030,7 +3030,7 @@ sub listDeviceGroupDevices {
 
 	return listDevice($device) if ($device ne '');
 
-	my $devices = $SCST->deviceGroupDevices($group);
+	my ($devices, $errorString) = $SCST->deviceGroupDevices($group);
 
 	my $l_device;
 	foreach my $device (@{$devices}) {
@@ -3058,7 +3058,7 @@ sub listDrivers {
 
 	return listTargets($driver, undef) if ($driver ne '');
 
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 
 	my $l_driver;
 	foreach my $driver (@{$drivers}) {
@@ -3088,7 +3088,7 @@ sub listTargets {
 
 	my $got_driver = ($driver ne '');
 
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 
 	my $l_driver;
 	my $l_target;
@@ -3101,7 +3101,7 @@ sub listTargets {
 
 			$l_driver = length($driver) if ($l_driver < length($driver));
 
-			my $targets = $SCST->targets($driver);
+			my ($targets, $errorString) = $SCST->targets($driver);
 
 			foreach my $target (@{$targets}) {
 				$l_target = length($target) if ($l_target < length($target));
@@ -3120,7 +3120,7 @@ sub listTargets {
 		my %p;
 
 		foreach my $driver (keys %toprint) {
-			my $targets = $SCST->targets($driver);
+			my ($targets, $errorString) = $SCST->targets($driver);
 
 			foreach my $target (@{$targets}) {
 				if (!defined($p{$driver})) {
@@ -3139,17 +3139,17 @@ sub listTargets {
 }
 
 sub listSessions {
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 
 	foreach my $driver (@{$drivers}) {
-		my $targets = $SCST->targets($driver);
+		my ($targets, $errorString) = $SCST->targets($driver);
 
 		foreach my $target (@{$targets}) {
 			my $had_sessions = FALSE;
 
 			print "Driver/Target: $driver/$target\n\n";
 
-			my $sessions = $SCST->sessions($driver, $target);
+			my ($sessions, $errorString) = $SCST->sessions($driver, $target);
 			foreach my $session (keys %{$sessions}) {
 				print "\tSession: $session\n\n";
 
@@ -3187,12 +3187,13 @@ sub listGroup {
 	my $group = shift;
 	my $luns = shift;
 	my $initiators = shift;
+	my $errorString;
 
-	$luns = $SCST->luns($driver, $target, $group) if (!$luns);
-	$initiators = $SCST->initiators($driver, $target, $group)
-	  if (($initiators eq '') && ($group ne ''));
-
-	return TRUE if issueWarning($SCST->errorString());
+	($luns, $errorString) = $SCST->luns($driver, $target, $group) if (!$luns);
+	if (($initiators eq '') && ($group ne '')) {
+		($initiators, $errorString) = $SCST->initiators($driver, $target, $group);
+		return TRUE if issueWarning($errorString);
+	}
 
 	if ((keys %{$luns}) || ($#{$initiators} > -1)) {
 		my $l_device;
@@ -3268,13 +3269,13 @@ sub listGroups {
 	my $got_target = $target;
 	my $got_driver = $driver;
 
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 
 	foreach my $_driver (@{$drivers}) {
 		$driver = $_driver if (!$got_driver);
 
 		if ($driver eq $_driver) {
-			my $targets = $SCST->targets($driver);
+			my ($targets, $errorString) = $SCST->targets($driver);
 			foreach my $_target (@{$targets}) {
 				$target = $_target if (!$got_target);
 
@@ -3287,7 +3288,7 @@ sub listGroups {
 
 					print "\n";
 
-					my $groups = $SCST->groups($driver, $target);
+					my ($groups, $errorString) = $SCST->groups($driver, $target);
 					foreach my $_group (@{$groups}) {
 						$group = $_group if (!$got_group);
 
@@ -3320,10 +3321,12 @@ sub listGroups {
 sub listExported {
 	my $device = shift;
 	my $attributes = shift;
+	my $errorString;
 
-	$attributes = $SCST->deviceAttributes($device) if (!$attributes);
-
-	return TRUE if issueWarning($SCST->errorString());
+	if (!$attributes) {
+		($attributes, $errorString) = $SCST->deviceAttributes($device) ;
+		return TRUE if issueWarning($errorString);
+	}
 
 	if (keys %{$$attributes{'exported'}}) {
 		my $exported = $$attributes{'exported'}->{'value'};
@@ -3491,9 +3494,9 @@ sub listAttributes {
 sub listScstAttributes {
 	my $nonkey = shift;
 
-	my $attributes = $SCST->scstAttributes();
+	my ($attributes, $errorString) = $SCST->scstAttributes();
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "FATAL: Unable to get a list of SCST attributes! Please make sure SCST is loaded.\n";
@@ -3507,9 +3510,9 @@ sub listHandlerAttributes {
 	my $handler = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->handlerAttributes($handler);
+	my ($attributes, $errorString) = $SCST->handlerAttributes($handler);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such handler '$handler' found.\n";
@@ -3519,9 +3522,9 @@ sub listHandlerAttributes {
 	my $rc = listAttributes($attributes, $nonkey);
 	return $rc if $rc;
 
-	$attributes = $SCST->deviceCreateAttributes($handler);
+	($attributes, $errorString) = $SCST->deviceCreateAttributes($handler);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 	return TRUE if (!scalar keys %{$attributes});
 
 	print "\n\tDevice CREATE attributes available\n";
@@ -3538,16 +3541,16 @@ sub listDriverAttributes {
 	my $driver = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->driverAttributes($driver);
+	my ($attributes, $errorString) = $SCST->driverAttributes($driver);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	my $rc = listAttributes($attributes, $nonkey);
 	return $rc if ($rc);
 
 	if ($SCST->driverIsVirtualCapable($driver)) {
-		$attributes = $SCST->driverDynamicAttributes($driver);
-		return TRUE if issueWarning($SCST->errorString());
+		($attributes, $errorString) = $SCST->driverDynamicAttributes($driver);
+		return TRUE if issueWarning($errorString);
 
 		if (scalar keys %{$attributes}) {
 			print "\n\tDynamic attributes available\n";
@@ -3558,9 +3561,9 @@ sub listDriverAttributes {
 			}
 		}
 
-		my $attributes = $SCST->targetCreateAttributes($driver);
+		my ($attributes, $errorString) = $SCST->targetCreateAttributes($driver);
 
-		return TRUE if issueWarning($SCST->errorString());
+		return TRUE if issueWarning($errorString);
 		return TRUE if (!scalar keys %{$attributes});
 
 		print "\n\tTarget CREATE attributes available:\n";
@@ -3579,9 +3582,9 @@ sub listTargetAttributes {
 	my $target = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->targetAttributes($driver, $target);
+	my ($attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such driver/target '$driver/$target' found.\n";
@@ -3592,8 +3595,8 @@ sub listTargetAttributes {
 	return $rc if $rc;
 
 	if ($SCST->driverIsVirtualCapable($driver)) {
-		$attributes = $SCST->targetDynamicAttributes($driver);
-		return TRUE if issueWarning($SCST->errorString());
+		($attributes, $errorString) = $SCST->targetDynamicAttributes($driver);
+		return TRUE if issueWarning($errorString);
 
 		if (scalar keys %{$attributes}) {
 			print "\n\tDynamic attributes available\n";
@@ -3605,9 +3608,9 @@ sub listTargetAttributes {
 		}
 	}
 
-	$attributes = $SCST->lunCreateAttributes($driver, $target);
+	($attributes, $errorString) = $SCST->lunCreateAttributes($driver, $target);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 	return TRUE if (!scalar keys %{$attributes});
 
 	print "\n\tLUN CREATE attributes available\n";
@@ -3626,9 +3629,9 @@ sub listGroupAttributes {
 	my $group = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->groupAttributes($driver, $target, $group);
+	my ($attributes, $errorString) = $SCST->groupAttributes($driver, $target, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such driver/target/group '$driver/$target/$group' found.\n";
@@ -3638,9 +3641,9 @@ sub listGroupAttributes {
 	my $rc = listAttributes($attributes, $nonkey);
 	return $rc if $rc;
 
-	$attributes = $SCST->lunCreateAttributes($driver, $target, $group);
+	($attributes, $errorString) = $SCST->lunCreateAttributes($driver, $target, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 	return TRUE if (!scalar keys %{$attributes});
 
 	print "\n\tLUN CREATE attributes available\n";
@@ -3650,9 +3653,9 @@ sub listGroupAttributes {
 		print "\t$attribute\n";
 	}
 
-	$attributes = $SCST->initiatorCreateAttributes($driver, $target, $group);
+	($attributes, $errorString) = $SCST->initiatorCreateAttributes($driver, $target, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 	return TRUE if (!scalar keys %{$attributes});
 
 	print "\n\tInitiator CREATE attributes available\n";
@@ -3672,9 +3675,9 @@ sub listLunAttributes {
 	my $lun = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->lunAttributes($driver, $target, $lun, $group);
+	my ($attributes, $errorString) = $SCST->lunAttributes($driver, $target, $lun, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		if ($group ne '') {
@@ -3695,16 +3698,16 @@ sub listInitiatorAttributes {
 	my $initiator = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->initiatorAttributes($driver, $target, $group, $initiator);
+	my ($attributes, $errorString) = $SCST->initiatorAttributes($driver, $target, $group, $initiator);
 
 	# As if writing, initiators didn't have attributes. This will
 	# allow us to support it in the future.
-	if ($SCST->errorString() =~ /Not a directory/) {
+	if ($errorString =~ /Not a directory/) {
 		print "Initiators do not (yet) have attributes.\n";
 		return;
 	}
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such driver/target/group/initiator '$driver/$target/$group/$initiator' found.\n";
@@ -3718,9 +3721,9 @@ sub listDeviceGroupAttributes {
 	my $group = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->deviceGroupAttributes($group);
+	my ($attributes, $errorString) = $SCST->deviceGroupAttributes($group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	# Special case - as of writing, device group attributes didn't exist.
 	if (!scalar(keys %{$attributes})) {
@@ -3736,9 +3739,9 @@ sub listTargetGroupAttributes {
 	my $tgroup = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->targetGroupAttributes($group, $tgroup);
+	my ($attributes, $errorString) = $SCST->targetGroupAttributes($group, $tgroup);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such device group/target group '$group/$tgroup' found.\n";
@@ -3754,9 +3757,9 @@ sub listTargetGroupTargetAttributes {
 	my $tgt = shift;
 	my $nonkey = shift;
 
-	my $attributes = $SCST->targetGroupTargetAttributes($group, $tgroup, $tgt, TRUE);
+	my ($attributes, $errorString) = $SCST->targetGroupTargetAttributes($group, $tgroup, $tgt, TRUE);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	if (!scalar(keys %{$attributes})) {
 		print "No such device group/target group/target '$group/$tgroup/$tgt' found.\n";
@@ -3788,9 +3791,9 @@ sub setScstAttributes {
 	my $showset = shift;
 
 	my $error = "\t-> WARNING: SCST lacks the settable attribute '%s', ignoring.\n\n";
-	my $_attributes = $SCST->scstAttributes();
+	my ($_attributes, $errorString) = $SCST->scstAttributes();
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, undef, undef, $attributes,
 	  $_attributes, $error, \&setScstAttribute, $showset);
@@ -3818,9 +3821,9 @@ sub setDeviceAttributes {
 
 	my $error = "\t-> WARNING: Device '$device' lacks the settable ".
 	  "attribute '%s', ignoring.\n\n";
-	my $_attributes = $SCST->deviceAttributes($device);
+	my ($_attributes, $errorString) = $SCST->deviceAttributes($device);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, undef, $device, $attributes,
 	  $_attributes, $error, \&setDeviceAttribute, $showset);
@@ -3848,9 +3851,9 @@ sub setHandlerAttributes {
 
 	my $error = "\t-> WARNING: Handler '$handler' lacks the settable ".
 	  "attribute '%s', ignoring.\n\n";
-	my $_attributes = $SCST->handlerAttributes($handler);
+	my ($_attributes, $errorString) = $SCST->handlerAttributes($handler);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, undef, $handler, $attributes,
 	  $_attributes, $error, \&setHandlerAttribute, $showset);
@@ -3881,9 +3884,9 @@ sub setGroupAttributes {
 
 	my $error = "\t-> WARNING: Driver/target/group '$driver/$target/$group' lacks the settable ".
 	  "attribute '%s', ignoring.\n\n";
-	my $_attributes = $SCST->groupAttributes($driver, $target, $group);
+	my ($_attributes, $errorString) = $SCST->groupAttributes($driver, $target, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, $driver, $target, $group, $attributes,
 	  $_attributes, $error, \&setGroupAttribute, $showset);
@@ -3928,9 +3931,9 @@ sub setLunAttributes {
 		  "attribute '%s', ignoring.\n\n";
 	}
 
-	my $_attributes = $SCST->lunAttributes($driver, $target, $lun, $group);
+	my ($_attributes, $errorString) = $SCST->lunAttributes($driver, $target, $lun, $group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes($driver, $target, $lun, $group, $attributes,
 	  $_attributes, $error, \&setLunAttribute, $showset);
@@ -3961,13 +3964,13 @@ sub setInitiatorAttributes {
 	my $attributes = shift;
 	my $showset = shift;
 
-	my $_attributes = $SCST->initiatorAttributes($driver, $target, $group, $initiator);
+	my ($_attributes, $errorString) = $SCST->initiatorAttributes($driver, $target, $group, $initiator);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	# As if writing, initiators didn't have attributes. This will
 	# allow us to support it in the future.
-	if ($SCST->errorString() =~ /Not a directory/) {
+	if ($errorString =~ /Not a directory/) {
 		print "Initiators do not (yet) have attributes.\n";
 		return;
 	}
@@ -3985,9 +3988,9 @@ sub setAluaAttributes {
 
 	my $error = "\t-> WARNING: no settable ALUA attribute '%s', ignoring.\n\n";
 
-	my $_attributes = $SCST->aluaAttributes();
+	my ($_attributes, $errorString) = $SCST->aluaAttributes();
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, undef, undef, $attributes,
 	  $_attributes, $error, \&setAluaAttribute, $showset);
@@ -4015,9 +4018,9 @@ sub setDeviceGroupAttributes {
 
 	my $error = "\t-> WARNING: Device Group '$group' lacks the settable attribute '%s', ignoring.\n\n";
 
-	my $_attributes = $SCST->deviceGroupAttributes($group);
+	my ($_attributes, $errorString) = $SCST->deviceGroupAttributes($group);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, undef, $group, $attributes,
 	  $_attributes, $error, \&setDeviceGroupAttribute, $showset);
@@ -4048,9 +4051,9 @@ sub setTargetGroupAttributes {
 
 	my $error = "\t-> WARNING: Target Group '$group/$tgroup' lacks the settable attribute '%s', ignoring.\n\n";
 
-	my $_attributes = $SCST->targetGroupAttributes($group, $tgroup);
+	my ($_attributes, $errorString) = $SCST->targetGroupAttributes($group, $tgroup);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, undef, $group, $tgroup, $attributes,
 	  $_attributes, $error, \&setTargetGroupAttribute, $showset);
@@ -4082,9 +4085,9 @@ sub setTargetGroupTargetAttributes {
 
 	my $error = "\t-> WARNING: Target '$group/$tgroup/$tgt' lacks the settable attribute '%s', ignoring.\n\n";
 
-	my $_attributes = $SCST->targetGroupTargetAttributes($group, $tgroup, $tgt, TRUE);
+	my ($_attributes, $errorString) = $SCST->targetGroupTargetAttributes($group, $tgroup, $tgt, TRUE);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	return setAttributes(undef, $group, $tgroup, $tgt, $attributes,
 	  $_attributes, $error, \&setTargetGroupTargetAttribute, $showset);
@@ -4184,9 +4187,9 @@ sub setDriverAttributes {
 	my $changes = 0;
 
 	my $driverCap = $SCST->driverIsVirtualCapable($driver);
-	my $_attributes = $SCST->driverAttributes($driver);
+	my ($_attributes, $errorString) = $SCST->driverAttributes($driver);
 
-	return 0 if issueWarning($SCST->errorString());
+	return 0 if issueWarning($errorString);
 
 	# build caches for easier matching
 	foreach my $attribute (keys %{$attributes}) {
@@ -4257,9 +4260,9 @@ sub addDriverDynamicAttributes {
 	my $driver = shift;
 	my $attributes = shift;
 
-	my $_attributes = $SCST->driverAttributes($driver);
+	my ($_attributes, $errorString) = $SCST->driverAttributes($driver);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	my $existing = cacheAttributes($_attributes);
 
@@ -4294,9 +4297,9 @@ sub removeDriverDynamicAttributes {
 	my $driver = shift;
 	my $attributes = shift;
 
-	my $_attributes = $SCST->driverAttributes($driver);
+	my ($_attributes, $errorString) = $SCST->driverAttributes($driver);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	my $existing = cacheAttributes($_attributes);
 
@@ -4360,9 +4363,9 @@ sub setTargetAttributes {
 	my $changes = 0;
 
 	my $driverCap = $SCST->driverIsVirtualCapable($driver);
-	my $_attributes = $SCST->targetAttributes($driver, $target);
+	my ($_attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
-	return 0 if issueWarning($SCST->errorString());
+	return 0 if issueWarning($errorString);
 
 	# build caches for easier matching
 	foreach my $attribute (keys %{$attributes}) {
@@ -4436,9 +4439,9 @@ sub addTargetDynamicAttributes {
 	my $target = shift;
 	my $attributes = shift;
 
-	my $_attributes = $SCST->targetAttributes($driver, $target);
+	my ($_attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	my $existing = cacheAttributes($_attributes);
 
@@ -4477,9 +4480,9 @@ sub removeTargetDynamicAttributes {
 	my $target = shift;
 	my $attributes = shift;
 
-	my $_attributes = $SCST->targetAttributes($driver, $target);
+	my ($_attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
-	return TRUE if issueWarning($SCST->errorString());
+	return TRUE if issueWarning($errorString);
 
 	my $existing = cacheAttributes($_attributes);
 
@@ -4537,7 +4540,7 @@ sub closeDevice {
 	my $device = shift;
 	my $force = shift;
 
-	my $attributes = $SCST->deviceAttributes($device);
+	my ($attributes, $errorString) = $SCST->deviceAttributes($device);
 
 	if (!$force) {
 		if (keys %{$$attributes{'exported'}}) {
@@ -4617,8 +4620,8 @@ sub removeDeviceGroup {
 	my $force = shift;
 
 	if (!$force) {
-		my $devices = $SCST->deviceGroupDevices($group);
-		my $tgroups = $SCST->targetGroups($group);
+		my ($devices, $errorString) = $SCST->deviceGroupDevices($group);
+		my ($tgroups, $errorString) = $SCST->targetGroups($group);
 
 		if (($#{$devices} > -1) || ($#{$tgroups} > -1)) {
 			print "\n";
@@ -4644,7 +4647,7 @@ sub removeTargetGroup {
 	my $force = shift;
 
 	if (!$force) {
-		my $tgts = $SCST->targetGroupTargets($group, $tgroup);
+		my ($tgts, $errorString) = $SCST->targetGroupTargets($group, $tgroup);
 
 		if ($#{$tgts} > -1) {
 			print "\n";
@@ -4703,10 +4706,10 @@ sub removeDeviceGroupDevice {
 
 	if (!$force) {
 		my $found = FALSE;
-		my $tgroups = $SCST->targetGroups($group);
+		my ($tgroups, $errorString) = $SCST->targetGroups($group);
 
 		foreach my $tgroup (@{$tgroups}) {
-			my $targets = $SCST->targetGroupTargets($group, $tgroup);
+			my ($targets, $errorString) = $SCST->targetGroupTargets($group, $tgroup);
 
 			if ($#{$targets} > -1) {
 				print "\n";
@@ -4756,8 +4759,8 @@ sub removeGroup {
 	my $force = shift;
 
 	if (!$force) {
-		my $luns = $SCST->luns($driver, $target, $group);
-		my $initiators = $SCST->initiators($driver, $target, $group);
+		my ($luns, $errorString) = $SCST->luns($driver, $target, $group);
+		my ($initiators, $errorString) = $SCST->initiators($driver, $target, $group);
 
 		if ((keys %{$luns}) || ($#{$initiators} > -1)) {
 			listGroup($driver, $target, $group, $luns, $initiators);
@@ -4959,8 +4962,8 @@ sub clearDriverDynamicAttributes {
 
 	print "\t-> Removing all dynamic attributes from driver '$driver': ";
 
-	my $attributes = $SCST->driverAttributes($driver);
-	my $dynamic = $SCST->driverDynamicAttributes($driver);
+	my ($attributes, $errorString) = $SCST->driverAttributes($driver);
+	my ($dynamic, $errorString) = $SCST->driverDynamicAttributes($driver);
 
 	foreach my $attribute (keys %{$attributes}) {
 		if (defined($$dynamic{$attribute})) {
@@ -4988,8 +4991,8 @@ sub clearTargetDynamicAttributes {
 
 	print "\t-> Removing all dynamic attributes from driver/target '$driver/$target': ";
 
-	my $attributes = $SCST->targetAttributes($driver, $target);
-	my $dynamic = $SCST->targetDynamicAttributes($driver);
+	my ($attributes, $errorString) = $SCST->targetAttributes($driver, $target);
+	my ($dynamic, $errorString) = $SCST->targetDynamicAttributes($driver);
 
 	foreach my $attribute (keys %{$attributes}) {
 		if (defined($$dynamic{$attribute})) {
@@ -5035,7 +5038,7 @@ sub enableDriver {
 	my $driver = shift;
 	my %attributes = ('enabled', 1);
 
-	my $attrs = $SCST->driverAttributes($driver);
+	my ($attrs, $errorString) = $SCST->driverAttributes($driver);
 	return TRUE if (!defined($$attrs{'enabled'}));
 
 	return setDriverAttributes($driver, \%attributes);
@@ -5045,7 +5048,7 @@ sub disableDriver {
 	my $driver = shift;
 	my %attributes = ('enabled', 0);
 
-	my $attrs = $SCST->driverAttributes($driver);
+	my ($attrs, $errorString) = $SCST->driverAttributes($driver);
 	return TRUE if (!defined($$attrs{'enabled'}));
 
 	return setDriverAttributes($driver, \%attributes);
@@ -5059,10 +5062,10 @@ sub issueLip {
 	if (defined($driver) && defined($target)) {
 		return _issueLip($driver, $target, $warn);
 	} else {
-		my $drivers = $SCST->drivers();
+		my ($drivers, $errorString) = $SCST->drivers();
 
 		foreach my $driver(@{$drivers}) {
-			my $targets = $SCST->targets($driver);
+			my ($targets, $errorString) = $SCST->targets($driver);
 
 			foreach my $target (@{$targets}) {
 				my $rc = _issueLip($driver, $target, $warn);
@@ -5081,7 +5084,7 @@ sub _issueLip {
 	my $warn = shift;
 	my $rc = FALSE;
 
-	my $attributes = $SCST->targetAttributes($driver, $target);
+	my ($attributes, $errorString) = $SCST->targetAttributes($driver, $target);
 
 	if (!defined($$attributes{'host'}) && $warn) {
 		print "\t-> Driver/target '$driver/$target' has no 'host' attribute, ignoring.\n";
@@ -5330,7 +5333,7 @@ sub readOldConfigFile {
 		}
 	}
 
-	my $drivers = $SCST->drivers();
+	my ($drivers, $errorString) = $SCST->drivers();
 	my %added_targets;
 
 	# Handle default groups
@@ -5342,7 +5345,7 @@ sub readOldConfigFile {
 				my($device, $lun) = split(/\,/, $device);
 
 				foreach my $driver (@{$drivers}) {
-					my $targets = $SCST->targets($driver);
+					my ($targets, $errorString) = $SCST->targets($driver);
 
 					foreach my $target (@{$targets}) {
 						$new{'TARGET_DRIVER'}->{$driver}->{'TARGET'}->{$target}->{'LUN'}->{$lun}->{$device} = {};
@@ -5355,7 +5358,7 @@ sub readOldConfigFile {
 			my $found_t = FALSE;
 			# Find the associated target
 			foreach my $driver (@{$drivers}) {
-				my $targets = $SCST->targets($driver);
+				my ($targets, $errorString) = $SCST->targets($driver);
 
 				foreach my $target (@{$targets}) {
 					if ($target eq $group_t) {
@@ -5407,7 +5410,7 @@ sub readOldConfigFile {
 
 		# Fill in with known targets, all disabled.
 		foreach my $driver (@{$drivers}) {
-			my $targets = $SCST->targets($driver);
+			my ($targets, $errorString) = $SCST->targets($driver);
 
 			foreach my $target (@{$targets}) {
 				addAllGroupsToTarget(\%config, \%new, $driver, $target);
@@ -5426,7 +5429,7 @@ sub readOldConfigFile {
 	foreach my $driver (keys %{$new{'TARGET_DRIVER'}}) {
 		next if ($driver =~ /^qla/);
 
-		my $attributes = $SCST->driverAttributes($driver);
+		my ($attributes, $errorString) = $SCST->driverAttributes($driver);
 
 		if (defined($$attributes{'enabled'})) {
 			$new{'TARGET_DRIVER'}->{$driver}->{'enabled'}->{'1'} = {};