diff --git a/weed/filer2/cassandra/cassandra_store.go b/weed/filer2/cassandra/cassandra_store.go
index a996a6401..8214935f9 100644
--- a/weed/filer2/cassandra/cassandra_store.go
+++ b/weed/filer2/cassandra/cassandra_store.go
@@ -2,6 +2,7 @@ package cassandra
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"github.com/gocql/gocql"
 
@@ -126,7 +127,7 @@ func (store *CassandraStore) DeleteFolderChildren(ctx context.Context, fullpath
 }
 
 func (store *CassandraStore) ListDirectoryPrefixedEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *CassandraStore) ListDirectoryEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool,
diff --git a/weed/filer2/etcd/etcd_store.go b/weed/filer2/etcd/etcd_store.go
index 043bf995d..93f3f3781 100644
--- a/weed/filer2/etcd/etcd_store.go
+++ b/weed/filer2/etcd/etcd_store.go
@@ -2,6 +2,7 @@ package etcd
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -136,7 +137,7 @@ func (store *EtcdStore) DeleteFolderChildren(ctx context.Context, fullpath weed_
 }
 
 func (store *EtcdStore) ListDirectoryPrefixedEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *EtcdStore) ListDirectoryEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool, limit int) (entries []*filer2.Entry, err error) {
diff --git a/weed/filer2/filer.go b/weed/filer2/filer.go
index cc8fecc42..ef81cae2b 100644
--- a/weed/filer2/filer.go
+++ b/weed/filer2/filer.go
@@ -18,7 +18,10 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/wdclient"
 )
 
-const PaginationSize = 1024 * 256
+const (
+	PaginationSize                      = 1024 * 256
+	UnsupportedListDirectoryPrefixedErr = "UNSUPPORTED"
+)
 
 var (
 	OS_UID = uint32(os.Getuid())
diff --git a/weed/filer2/filerstore.go b/weed/filer2/filerstore.go
index 9ea39cf11..3c1e555b1 100644
--- a/weed/filer2/filerstore.go
+++ b/weed/filer2/filerstore.go
@@ -138,7 +138,7 @@ func (fsw *FilerStoreWrapper) ListDirectoryPrefixedEntries(ctx context.Context,
 		stats.FilerStoreHistogram.WithLabelValues(fsw.ActualStore.GetName(), "list").Observe(time.Since(start).Seconds())
 	}()
 	entries, err := fsw.ActualStore.ListDirectoryPrefixedEntries(ctx, dirPath, startFileName, includeStartFile, limit, prefix)
-	if err.Error() == "UNSUPPORTED" {
+	if err.Error() == UnsupportedListDirectoryPrefixedErr {
 		count := 0
 		notPrefixed, err := fsw.ActualStore.ListDirectoryEntries(ctx, dirPath, startFileName, includeStartFile, limit)
 		if err != nil {
@@ -179,11 +179,6 @@ func (fsw *FilerStoreWrapper) ListDirectoryPrefixedEntries(ctx context.Context,
 	return entries, nil
 }
 
-func (fsw *FilerStoreWrapper) ListDirectoryUnSupPrefixedEntries(ctx context.Context, dirPath util.FullPath, startFileName string, includeStartFile bool, limit int, prefix string) (entries []*Entry, err error) {
-
-	return entries, nil
-}
-
 func (fsw *FilerStoreWrapper) BeginTransaction(ctx context.Context) (context.Context, error) {
 	return fsw.ActualStore.BeginTransaction(ctx)
 }
diff --git a/weed/filer2/leveldb/leveldb_store.go b/weed/filer2/leveldb/leveldb_store.go
index 104e3d026..787671c55 100644
--- a/weed/filer2/leveldb/leveldb_store.go
+++ b/weed/filer2/leveldb/leveldb_store.go
@@ -3,9 +3,10 @@ package leveldb
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"github.com/syndtr/goleveldb/leveldb"
-	"github.com/syndtr/goleveldb/leveldb/errors"
+	leveldb_errors "github.com/syndtr/goleveldb/leveldb/errors"
 	"github.com/syndtr/goleveldb/leveldb/opt"
 	leveldb_util "github.com/syndtr/goleveldb/leveldb/util"
 
@@ -49,7 +50,7 @@ func (store *LevelDBStore) initialize(dir string) (err error) {
 	}
 
 	if store.db, err = leveldb.OpenFile(dir, opts); err != nil {
-		if errors.IsCorrupted(err) {
+		if leveldb_errors.IsCorrupted(err) {
 			store.db, err = leveldb.RecoverFile(dir, opts)
 		}
 		if err != nil {
@@ -159,7 +160,7 @@ func (store *LevelDBStore) DeleteFolderChildren(ctx context.Context, fullpath we
 }
 
 func (store *LevelDBStore) ListDirectoryPrefixedEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *LevelDBStore) ListDirectoryEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool,
diff --git a/weed/filer2/leveldb2/leveldb2_store.go b/weed/filer2/leveldb2/leveldb2_store.go
index 478661d0e..4fc110d69 100644
--- a/weed/filer2/leveldb2/leveldb2_store.go
+++ b/weed/filer2/leveldb2/leveldb2_store.go
@@ -4,9 +4,10 @@ import (
 	"bytes"
 	"context"
 	"crypto/md5"
+	"errors"
 	"fmt"
 	"github.com/syndtr/goleveldb/leveldb"
-	"github.com/syndtr/goleveldb/leveldb/errors"
+	leveldb_errors "github.com/syndtr/goleveldb/leveldb/errors"
 	"github.com/syndtr/goleveldb/leveldb/opt"
 	leveldb_util "github.com/syndtr/goleveldb/leveldb/util"
 	"io"
@@ -52,7 +53,7 @@ func (store *LevelDB2Store) initialize(dir string, dbCount int) (err error) {
 		dbFolder := fmt.Sprintf("%s/%02d", dir, d)
 		os.MkdirAll(dbFolder, 0755)
 		db, dbErr := leveldb.OpenFile(dbFolder, opts)
-		if errors.IsCorrupted(dbErr) {
+		if leveldb_errors.IsCorrupted(dbErr) {
 			db, dbErr = leveldb.RecoverFile(dbFolder, opts)
 		}
 		if dbErr != nil {
@@ -168,7 +169,7 @@ func (store *LevelDB2Store) DeleteFolderChildren(ctx context.Context, fullpath w
 }
 
 func (store *LevelDB2Store) ListDirectoryPrefixedEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *LevelDB2Store) ListDirectoryEntries(ctx context.Context, fullpath weed_util.FullPath, startFileName string, inclusive bool,
diff --git a/weed/filer2/mongodb/mongodb_store.go b/weed/filer2/mongodb/mongodb_store.go
index 1fa18f872..314f36ce2 100644
--- a/weed/filer2/mongodb/mongodb_store.go
+++ b/weed/filer2/mongodb/mongodb_store.go
@@ -2,6 +2,7 @@ package mongodb
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"github.com/chrislusf/seaweedfs/weed/filer2"
 	"github.com/chrislusf/seaweedfs/weed/glog"
@@ -168,7 +169,7 @@ func (store *MongodbStore) DeleteFolderChildren(ctx context.Context, fullpath ut
 }
 
 func (store *MongodbStore) ListDirectoryPrefixedEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *MongodbStore) ListDirectoryEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool, limit int) (entries []*filer2.Entry, err error) {
diff --git a/weed/filer2/redis/universal_redis_store.go b/weed/filer2/redis/universal_redis_store.go
index 9c71b045d..66450b5a7 100644
--- a/weed/filer2/redis/universal_redis_store.go
+++ b/weed/filer2/redis/universal_redis_store.go
@@ -2,6 +2,7 @@ package redis
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sort"
 	"strings"
@@ -122,7 +123,7 @@ func (store *UniversalRedisStore) DeleteFolderChildren(ctx context.Context, full
 }
 
 func (store *UniversalRedisStore) ListDirectoryPrefixedEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *UniversalRedisStore) ListDirectoryEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool,
diff --git a/weed/filer2/redis2/universal_redis_store.go b/weed/filer2/redis2/universal_redis_store.go
index 6490f7bed..9878799cf 100644
--- a/weed/filer2/redis2/universal_redis_store.go
+++ b/weed/filer2/redis2/universal_redis_store.go
@@ -2,6 +2,7 @@ package redis2
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -117,7 +118,7 @@ func (store *UniversalRedis2Store) DeleteFolderChildren(ctx context.Context, ful
 }
 
 func (store *UniversalRedis2Store) ListDirectoryPrefixedEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool, limit int, prefix string) (entries []*filer2.Entry, err error) {
-	return nil, fmt.Errorf("UNSUPPORTED")
+	return nil, errors.New(filer2.UnsupportedListDirectoryPrefixedErr)
 }
 
 func (store *UniversalRedis2Store) ListDirectoryEntries(ctx context.Context, fullpath util.FullPath, startFileName string, inclusive bool,