diff --git a/transport/server.cc b/transport/server.cc
index 448b128123..13f16c20df 100644
--- a/transport/server.cc
+++ b/transport/server.cc
@@ -37,12 +37,6 @@ struct cql_frame_error : std::exception {
     }
 };
 
-struct bad_cql_protocol_version : std::exception {
-    const char* what() const throw () override {
-        return "bad cql binary protocol version";
-    }
-};
-
 struct [[gnu::packed]] cql_binary_frame_v1 {
     uint8_t  version;
     uint8_t  flags;
@@ -207,8 +201,22 @@ public:
         _server._notifier->unregister_connection(this);
     }
     future<> process() {
-        return do_until([this] { return _read_buf.eof(); }, [this] { return process_request(); })
-        .finally([this] {
+        return do_until([this] {
+            return _read_buf.eof();
+        }, [this] {
+            return process_request();
+        }).then_wrapped([this] (future<> f) {
+            try {
+                f.get();
+                return make_ready_future<>();
+            } catch (const exceptions::cassandra_exception& ex) {
+                return write_error(0, ex.code(), ex.what());
+            } catch (std::exception& ex) {
+                return write_error(0, exceptions::exception_code::SERVER_ERROR, ex.what());
+            } catch (...) {
+                return write_error(0, exceptions::exception_code::SERVER_ERROR, "unknown error");
+            }
+        }).finally([this] {
             return _pending_requests_gate.close().then([this] {
                 return std::move(_ready_to_respond);
             });
@@ -625,10 +633,11 @@ cql_server::connection::parse_frame(temporary_buffer<char> buf) {
         break;
     }
     default:
-        abort();
+        throw exceptions::protocol_exception(sprint("Invalid or unsupported protocol version: %d", _version));
     }
     if (v3.version != _version) {
-        throw bad_cql_protocol_version();
+        throw exceptions::protocol_exception(sprint("Invalid message version. Got %d but previous messages on this connection had version %d", v3.version, _version));
+
     }
     return v3;
 }
@@ -645,8 +654,8 @@ cql_server::connection::read_frame() {
             }
             _version = buf[0];
             init_serialization_format();
-            if (_version < 1 || _version > 4) {
-                throw bad_cql_protocol_version();
+            if (_version < 1 || _version > current_version) {
+                throw exceptions::protocol_exception(sprint("Invalid or unsupported protocol version: %d", _version));
             }
             return _read_buf.read_exactly(frame_size() - 1).then([this] (temporary_buffer<char> tail) {
                 temporary_buffer<char> full(frame_size());
diff --git a/transport/server.hh b/transport/server.hh
index 19669780b3..7e1c283afb 100644
--- a/transport/server.hh
+++ b/transport/server.hh
@@ -24,6 +24,8 @@ class database;
 class cql_server {
     class event_notifier;
 
+    static constexpr int current_version = 3;
+
     std::vector<server_socket> _listeners;
     distributed<service::storage_proxy>& _proxy;
     distributed<cql3::query_processor>& _query_processor;