VSSControl failed for the vm that runs Veeam M365 backup

[bmaster001]

We use Veeam B&R to backup (amongst other of course) the Windows VM that runs Veeam Backup for MS 365. The backup of this VM fails with the error "Failed to prepare guest for hot backup. Error: VSSControl: Failed to prepare guest for freeze, wait timeout 900 sec". I think, but I'm not 100% sure, that this happens since we upgraded Veeam M365 to version 12 with the postgresql database.
In the Application-aware processing, I can add the M365 VM and in the settings there is a PostgreSQL tab but I don't know what to enter there. Maybe I should disable application processing for this VM? Any suggestions welcome!

[david.domask]

Hi bmaster001,

May I ask you to start with this KB to attempt to address the VSS Preparation timeout? The preparation stage in VSS happens before the diskshadow creation, so extending this timeout is safe and normal, but sometimes the preparation may take longer than the default 900 seconds. Sometimes certain writers take a bit longer on the preparation step, and from experience, usually just a successful Application Aware backup helps resolve it. The timeout controls simply how long Veeam will wait for the VSS preparation step, which should be quick in most cases -- subsequent runs typically are much faster (no need to remove the registry values the KB tells to set)

Try a value of 1800000 for VssPreparationTimeout to start with.

If it doesn't help, then it's best to open a Support Case and let Veeam Support review the behavior. Be sure to include logs for the affected job and share your case number here please.

Thanks!

[bmaster001]

Ok, thanks, I'll do that and wait for the next backup run.

[bmaster001]

Problem stays the same with the increased timeout. I created a support ticket: #07454256

[Mildur]

Hi bmaster001

I recommend to install our latest patch for VB365 v8. One of the issues solved by the patch is VSS timeout in VBR backup jobs of the VB365 machine.

Veeam Backup for Microsoft 365 v8 - P20241008 (8.0.3.1044)
https://www.veeam.com/kb4656

Resolved Issues

Backing up your Veeam Backup for Microsoft 365 server with Veeam Backup and Replication with Guest indexing enabled fails with a VSS timeout.

Best,
Fabian

[bmaster001]

Support suggested to try disabling the antivirus software. I did that yesterday, and the backup was successful this night. I now re-enabled the antivirus, and upgraded to 8.0.3.1044 as per your suggestion. We'll see what happens next night!