[ovirt-users] Cannot delete the snapshot

Dear all, This is my first time to ask question in this place. Thank you for time to read my question first. Yesterday, i wanted to delete the snapshot on oVirt Engine Web Administration. However, it took so long to delete a snapshot and it still in process. Due to the "snapshot error", i cannot run the virtual machine as i shut it down before. Is there anyone has some idea how to fix it? The following information maybe useful for debugging . On web administration: Removing Snapshot <the snapshot name> Sep 1, 2017 6:06:58 PM N/A <the snapshot id> <green tick>Validating Sep 1, 2017 6:06:58 PM until Sep 1, 2017 6:06:58 PM <In process> Executing Sep 1, 2017 6:06:58 PM N/A On Engine log. 2017-09-02 20:57:10,700+08 INFO [org.ovirt.engine.core.bll.ConcurrentChildCommandsExecutionCallback] (DefaultQuartzScheduler6) [70471886-a5cb-404c-80db-b8469092aa8e] Command 'RemoveSnapshot' (id: '78ee1e62-26ea-403d-b518-9e3d3be995c2') waiting on child command id: '5f2e8197-704f-453c-bea8-74186e5ca95c' type:'RemoveSnapshotSingleDiskLive' to complete