VCS sync: TreeNode not initialized

I just want to sync VAR layer. I got the error as below. Does anyone know how to fix this problem? Any hint will be appreciated.

Error executing code: TreeNode object not initialized.

Stack trace

(C)\Classes\TreeNode\applObjectLayerMask

(C)\Data Dictionary\Tables\SysVersionControlSynchronizeLog\Methods\processModelInBatchNum - line 57

(C)\Data Dictionary\Tables\SysVersionControlSynchronizeLog\Methods\processBatchNum - line 26

(C)\Classes\SysVersionControlSystemFileBased\commandSynchronize - line 127

(C)\Classes\VersionControl\getLatestVersion - line 22

(C)\Classes\SysVersionControlSynchronization\run - line 28

(C)\Classes\SysVersionControlSynchronization\main - line 23