vCenterServer: "Unable to connect to quest OS for quest processing" after updating Veeam B&R to 12

[x-swk]

CaseID: 06138544
Additional Details: After Updating Veeam B&R from Version 11 to Version 12, I get this error

for vCenter Server VM.

Unable to connect to guest OS for guest processing. Failed to connect to host

Error: Invalid command.

Processing finished with errors..

[HannesK]

Hello,
and welcome to the forums.

Let's see what support finds out. It makes little sense to speculate on a forum for this type of error.

Best regards,
Hannes

[x-swk]

Case was closed by Veeam, no time for supporting Community Edition.
After reading vCenter Server Appliance - Backup/Restore Recommendations, I've disabled this Point:
(Required) Disable Application-Aware Processing and Guest File System Indexing within the job for the VCSA VM
and Backup works fine.

[d.artzen]

I can't remember where exactly I read that, but I have read somewhere that a VM-level Backup of the Vcenter Appliance is not recommended. The recommended way to backup the Vcenter is to use the in-build Backup function of the Vcenter, which saves the configuration database in a file-level format. Without the Application Aware Processing it could be possible that the database in the backup is in an inconsistent state.
We have scheduled a weekly backup this way. We also excluded the Vcenter VM in our VBR and instead backup the FTP-Server, where the Vcenter Backup Files are stored. In case that the Vcenter is in an irreparable state the way to restore would be to install a new VM in the same version and then do a restore of the configuration from there.