diff --git a/backend/app/migrator/migrator_test.go b/backend/app/migrator/migrator_test.go
index 0ebcd09e..75bc40b5 100644
--- a/backend/app/migrator/migrator_test.go
+++ b/backend/app/migrator/migrator_test.go
@@ -5,7 +5,7 @@ import (
 	"os"
 	"testing"
 
-	"github.com/coreos/bbolt"
+	bolt "github.com/coreos/bbolt"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -66,13 +66,13 @@ func TestMigrator_ImportWordPress(t *testing.T) {
 	assert.Equal(t, 3, len(last), "3 comments imported")
 }
 
-func TestMigrator_ImportRemark(t *testing.T) {
+func TestMigrator_ImportNative(t *testing.T) {
 	defer func() {
 		os.Remove("/tmp/remark-test.db")
 		os.Remove("/tmp/disqus-test.r42")
 	}()
 
-	data := `{"id":"efbc17f177ee1a1c0ee6e1e025749966ec071adc","pid":"","text":"some text, <a href=\"http://radio-t.com\" rel=\"nofollow\">link</a>","user":{"name":"user name","id":"user1","picture":"","profile":"","admin":false},"locator":{"site":"radio-t","url":"https://radio-t.com"},"score":0,"votes":{},"time":"2017-12-20T15:18:22-06:00"}` + "\n" +
+	data := `{"version":1} {"id":"efbc17f177ee1a1c0ee6e1e025749966ec071adc","pid":"","text":"some text, <a href=\"http://radio-t.com\" rel=\"nofollow\">link</a>","user":{"name":"user name","id":"user1","picture":"","profile":"","admin":false},"locator":{"site":"radio-t","url":"https://radio-t.com"},"score":0,"votes":{},"time":"2017-12-20T15:18:22-06:00"}` + "\n" +
 		`{"id":"afbc17f177ee1a1c0ee6e1e025749966ec071adc","pid":"efbc17f177ee1a1c0ee6e1e025749966ec071adc","text":"some text2, <a href=\"http://radio-t.com\" rel=\"nofollow\">link</a>","user":{"name":"user name","id":"user1","picture":"","profile":"","admin":false},"locator":{"site":"radio-t","url":"https://radio-t.com"},"score":0,"votes":{},"time":"2017-12-20T15:18:23-06:00"}` + "\n"
 
 	err := ioutil.WriteFile("/tmp/disqus-test.r42", []byte(data), 0600)
diff --git a/backend/app/migrator/native.go b/backend/app/migrator/native.go
index 05e73ce5..abb06eb2 100644
--- a/backend/app/migrator/native.go
+++ b/backend/app/migrator/native.go
@@ -12,6 +12,8 @@ import (
 	"github.com/umputun/remark/backend/app/store/service"
 )
 
+const natvieVersion = 1
+
 // Native implements exporter and importer for internal store format
 // {"version": 1, comments:[{...}\n,{}], meta: {meta}}
 // each comments starts from the new line
@@ -68,7 +70,7 @@ func (n *Native) Export(w io.Writer, siteID string) (size int, err error) {
 
 // exportMeta appends user and post metas to exported stream
 func (n *Native) exportMeta(siteID string, w io.Writer) (err error) {
-	m := meta{Version: 1}
+	m := meta{Version: natvieVersion}
 	m.Users, m.Posts, err = n.DataStore.Metas(siteID)
 	if err != nil {
 		return errors.Wrap(err, "can't get meta")
@@ -89,7 +91,11 @@ func (n *Native) Import(reader io.Reader, siteID string) (size int, err error) {
 		return 0, errors.Wrapf(err, "failed to import meta for site %s", siteID)
 	}
 
-	if err := n.DataStore.DeleteAll(siteID); err != nil {
+	if m.Version != natvieVersion {
+		return 0, errors.Errorf("unexpected import file version %d", m.Version)
+	}
+
+	if err = n.DataStore.DeleteAll(siteID); err != nil {
 		return 0, err
 	}
 
@@ -110,7 +116,7 @@ func (n *Native) Import(reader io.Reader, siteID string) (size int, err error) {
 			continue
 		}
 
-		if _, err := n.DataStore.Create(comment); err != nil {
+		if _, err = n.DataStore.Create(comment); err != nil {
 			failed++
 			log.Printf("[WARN] can't write %+v to store, %s", comment, err)
 			continue
diff --git a/backend/app/migrator/native_test.go b/backend/app/migrator/native_test.go
index 8cadfdfa..46ebcc36 100644
--- a/backend/app/migrator/native_test.go
+++ b/backend/app/migrator/native_test.go
@@ -100,6 +100,18 @@ func TestNative_Import(t *testing.T) {
 	assert.Equal(t, false, b.IsVerified("radio-t", "user2"))
 }
 
+func TestNative_ImportWrongVersion(t *testing.T) {
+	inp := `{"version":2,"users":[{"id":"user1","blocked":{"status":false,"until":"0001-01-01T00:00:00Z"},"verified":true},{"id":"user2","blocked":{"status":true,"until":"2018-12-23T02:55:22.472041-06:00"},"verified":false}],"posts":[{"url":"https://radio-t.com","read_only":true}]}
+	{"id":"efbc17f177ee1a1c0ee6e1e025749966ec071adc","pid":"","text":"some text, <a href=\"http://radio-t.com\" rel=\"nofollow\">link</a>","user":{"name":"user name","id":"user1","picture":"","ip":"293ec5b0cf154855258824ec7fac5dc63d176915","admin":false},"locator":{"site":"radio-t","url":"https://radio-t.com"},"score":0,"votes":{},"time":"2017-12-20T15:18:22-06:00"}
+	{"id":"f863bd79-fec6-4a75-b308-61fe5dd02aa1","pid":"1234","text":"some text2","user":{"name":"user name","id":"user2","picture":"","ip":"293ec5b0cf154855258824ec7fac5dc63d176915","admin":false},"locator":{"site":"radio-t","url":"https://radio-t.com/2"},"score":0,"votes":{},"time":"2017-12-20T15:18:23-06:00"}`
+
+	b := prep(t) // write some recs
+	r := Native{DataStore: &service.DataStore{Interface: b, AdminStore: admin.NewStaticStore("12345", []string{}, "")}}
+	size, err := r.Import(strings.NewReader(inp), "radio-t")
+	assert.EqualError(t, err, "unexpected import file version 2")
+	assert.Equal(t, 0, size)
+
+}
 func TestNative_ImportManyWithError(t *testing.T) {
 	defer os.Remove(testDb)
 
diff --git a/backend/app/rest/api/admin_test.go b/backend/app/rest/api/admin_test.go
index 24fed171..8258cadc 100644
--- a/backend/app/rest/api/admin_test.go
+++ b/backend/app/rest/api/admin_test.go
@@ -455,7 +455,7 @@ func TestAdmin_ExportStream(t *testing.T) {
 
 	body, code := getWithAuth(t, ts.URL+"/api/v1/admin/export?site=radio-t&mode=stream")
 	assert.Equal(t, 200, code)
-	assert.Equal(t, 6, strings.Count(body, "\n"))
+	assert.Equal(t, 3, strings.Count(body, "\n"))
 	assert.Equal(t, 2, strings.Count(body, "\"text\""))
 	t.Logf("%s", body)
 }
@@ -487,7 +487,7 @@ func TestAdmin_ExportFile(t *testing.T) {
 	assert.NoError(t, err)
 	ungzBody, err := ioutil.ReadAll(ungzReader)
 	assert.NoError(t, err)
-	assert.Equal(t, 6, strings.Count(string(ungzBody), "\n"))
+	assert.Equal(t, 3, strings.Count(string(ungzBody), "\n"))
 	assert.Equal(t, 2, strings.Count(string(ungzBody), "\"text\""))
 	t.Logf("%s", string(ungzBody))
 }
diff --git a/backend/app/rest/api/migrator_test.go b/backend/app/rest/api/migrator_test.go
index da860b25..83fa652a 100644
--- a/backend/app/rest/api/migrator_test.go
+++ b/backend/app/rest/api/migrator_test.go
@@ -34,7 +34,7 @@ func TestMigrator_Import(t *testing.T) {
 	assert.NotNil(t, srv)
 	defer cleanupImportSrv(srv, ts)
 
-	r := strings.NewReader(`{"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
+	r := strings.NewReader(`{"version":1} {"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
 	{"id":"83fd97fd-ff64-48d1-9fb7-ca7769c77037","pid":"p1","text":"<p>test test #2</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah2"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.861387771-05:00"}`)
 
 	client := &http.Client{Timeout: 1 * time.Second}
@@ -61,7 +61,7 @@ func TestMigrator_ImportForm(t *testing.T) {
 	assert.NotNil(t, srv)
 	defer cleanupImportSrv(srv, ts)
 
-	r := strings.NewReader(`{"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
+	r := strings.NewReader(`{"version":1} {"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
 	{"id":"83fd97fd-ff64-48d1-9fb7-ca7769c77037","pid":"p1","text":"<p>test test #2</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah2"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.861387771-05:00"}`)
 
 	bodyBuf := &bytes.Buffer{}
@@ -136,7 +136,7 @@ func TestMigrator_ImportRejected(t *testing.T) {
 	assert.NotNil(t, srv)
 	defer cleanupImportSrv(srv, ts)
 
-	r := strings.NewReader(`{"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
+	r := strings.NewReader(`{"version":1} {"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
 	{"id":"83fd97fd-ff64-48d1-9fb7-ca7769c77037","pid":"p1","text":"<p>test test #2</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah2"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.861387771-05:00"}`)
 
 	client := &http.Client{Timeout: 1 * time.Second}
@@ -157,7 +157,7 @@ func TestMigrator_ImportDouble(t *testing.T) {
 	for i := 0; i < 1000; i++ {
 		recs = append(recs, fmt.Sprintf(tmpl, i))
 	}
-	r := strings.NewReader(strings.Join(recs, "\n")) // reader with 10k records
+	r := strings.NewReader(`{"version":1}` + strings.Join(recs, "\n")) // reader with 10k records
 	client := &http.Client{Timeout: 1 * time.Second}
 	req, err := http.NewRequest("POST", ts.URL+"/import?site=radio-t&provider=native&secret=123456", r)
 	assert.Nil(t, err)
@@ -184,7 +184,7 @@ func TestMigrator_ImportWaitExpired(t *testing.T) {
 	for i := 0; i < 1000; i++ {
 		recs = append(recs, fmt.Sprintf(tmpl, i))
 	}
-	r := strings.NewReader(strings.Join(recs, "\n")) // reader with 10k records
+	r := strings.NewReader(`{"version":1}` + strings.Join(recs, "\n")) // reader with 10k records
 	client := &http.Client{Timeout: 1 * time.Second}
 	req, err := http.NewRequest("POST", ts.URL+"/import?site=radio-t&provider=native&secret=123456", r)
 	require.Nil(t, err)
@@ -205,7 +205,7 @@ func TestMigrator_Export(t *testing.T) {
 	assert.NotNil(t, srv)
 	defer cleanupImportSrv(srv, ts)
 
-	r := strings.NewReader(`{"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
+	r := strings.NewReader(`{"version":1} {"id":"2aa0478c-df1b-46b1-b561-03d507cf482c","pid":"","text":"<p>test test #1</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah1"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.849053725-05:00"}
 	{"id":"83fd97fd-ff64-48d1-9fb7-ca7769c77037","pid":"p1","text":"<p>test test #2</p>","user":{"name":"developer one","id":"dev","picture":"/api/v1/avatar/remark.image","profile":"https://remark42.com","admin":true,"ip":"ae12fe3b5f129b5cc4cdd2b136b7b7947c4d2741"},"locator":{"site":"radio-t","url":"https://radio-t.com/blah2"},"score":0,"votes":{},"time":"2018-04-30T01:37:00.861387771-05:00"}`)
 
 	// import comments first
@@ -234,7 +234,7 @@ func TestMigrator_Export(t *testing.T) {
 	assert.NoError(t, err)
 	ungzBody, err := ioutil.ReadAll(ungzReader)
 	assert.NoError(t, err)
-	assert.Equal(t, 6, strings.Count(string(ungzBody), "\n"))
+	assert.Equal(t, 3, strings.Count(string(ungzBody), "\n"))
 	assert.Equal(t, 2, strings.Count(string(ungzBody), "\"text\""))
 	t.Logf("%s", string(ungzBody))
 
@@ -248,7 +248,7 @@ func TestMigrator_Export(t *testing.T) {
 
 	body, err := ioutil.ReadAll(resp.Body)
 	assert.NoError(t, err)
-	assert.Equal(t, 6, strings.Count(string(body), "\n"))
+	assert.Equal(t, 3, strings.Count(string(body), "\n"))
 	assert.Equal(t, 2, strings.Count(string(body), "\"text\""))
 	t.Logf("%s", string(body))
 
diff --git a/backend/app/store/service/service.go b/backend/app/store/service/service.go
index 56ab2f58..6a5d94c3 100644
--- a/backend/app/store/service/service.go
+++ b/backend/app/store/service/service.go
@@ -295,7 +295,7 @@ func (s *DataStore) SetMetas(siteID string, umetas []UserMetaData, pmetas []Post
 	// save users metas
 	for _, um := range umetas {
 		if um.Blocked.Status {
-			errs = multierror.Append(errs, s.SetBlock(siteID, um.ID, true, um.Blocked.Until.Sub(time.Now())))
+			errs = multierror.Append(errs, s.SetBlock(siteID, um.ID, true, time.Until(um.Blocked.Until)))
 		}
 		if um.Verified {
 			errs = multierror.Append(errs, s.SetVerified(siteID, um.ID, true))