diff --git a/kernel/model/sync.go b/kernel/model/sync.go
index a913371e5..33e51cf2c 100644
--- a/kernel/model/sync.go
+++ b/kernel/model/sync.go
@@ -1112,6 +1112,8 @@ func CreateCloudSyncDir(name string) (err error) {
 	syncLock.Lock()
 	defer syncLock.Unlock()
 
+	name = strings.TrimSpace(name)
+	name = util.RemoveInvisible(name)
 	if !IsValidCloudDirName(name) {
 		return errors.New(Conf.Language(37))
 	}
@@ -1197,7 +1199,10 @@ func formatErrorMsg(err error) string {
 }
 
 func IsValidCloudDirName(cloudDirName string) bool {
-	if 64 < len(cloudDirName) {
+	if "backup" == cloudDirName {
+		return false
+	}
+	if 16 < len(cloudDirName) {
 		return false
 	}