Failed full backup with VSS error code

I’m using UrBackup Server 2.3.8 on a Ubuntu Server 16.04 and client 2.3.4 on Windows 2016 Server. This client in the last 2 weeks perform backup succefully but, in the last two days, full backup fail with error:

backupcom->StartSnapshotSet(&dir->ref->ssetid) failed. VSS error code VSS_E_SNAPSHOT_SET_IN_PROGRESS|

Indexing Windows components failed|
Constructing of filelist of “buonocoregis” failed: error - index error
Backup had an early error. Deleting partial backup.

What may have happened? How can I investigate?

Help me, please!


VSS errors are usually in the Windows Event Log (view using Event Viewer).

Ok @uroni i’m check VSS event in Windows Event Log.
Meanwhile, can I bypass the problem disabling VSS snaphot on UrBackup Server for this client and perform backups?

Also, check out vssadmin command, specfically vssadmin list writers. Make sure no other backup program is running that may use vss as well. Someone in my domain, had a scheduled vss via task scheduler, so that may be a good place to look as well.

I checked, there are no scheduled processes in task manager. I restarted windows and successfully completed a full backup. The next incremental backup reported the same errors!

It is strange? Why the full backup is ok and the incremental one is not?