Backing Up Contained Availability Group System Database (<Contained ag>_master) in Veeam SQL Backup

[steffen_engel]

Support ID: #02652696
Product: Veeam Backup & Replication v13
Environment: Microsoft SQL Server 2022 Enterprise, contained Always On Availability Group

Issue Summary:
When attempting to back up a contained Always On Availability Group using Veeam (both Veeam SQL Plug-In and Veeam Agent / Application-Aware Processing), the job fails with the following error:

Error: Database <Contained ag>_master contains system databases.
Failed to check backup prerequisites for Database <Contained ag>_master

This occurs both with:
Veeam SQL Backup Plug-In, when adding the contained AG databases to the backup job.
Veeam Agent for Windows (App-Aware / Cluster Backup) configured to back up the Always On Availability Group.
The error indicates that Veeam identifies <Contained ag>_master as a system database and blocks the backup prerequisite check.

Steps Taken:

- Verified that the AG configuration is correct and that the contained AG is functioning normally.
- Confirmed that image-level backups with application-aware processing work for other AG databases on the same instance.
- Attempted native SQL backups manually via SQL Server and confirmed that these work outside of Veeam.
- Tested both primary and secondary replicas in the backup job.
- takenMSSQLNative Backups of all Database,Tested Restore of all Databases (inkl.<Contained ag>_master)

Problem Details / Technical Impact:
Contained availability groups introduce “contained” system databases (such as <Contained ag>_master and potentially <Contained ag>_msdb). However, Veeam appears to treat these as regular SQL system databases and rejects them during the backup prerequisite check, preventing both full and transaction log backups via the Plug-In or Agent. This means the AG cannot be fully protected using Veeam’s native SQL backup mechanisms.

Expected Behavior:
Veeam should support backups of contained availability groups in SQL Server 2022, including correctly handling contained AG system databases as part of an AG backup scenario, or at least provide guidance on how to exclude or otherwise manage these objects without causing the backup to fail. Backup all Databases in <Contained AG>inkl. <Contained ag>_master & <Contained ag>_msdb as normal User Database.

Hint: if you connect to an instance act as Contained AG Primary you will see <Contained ag>_master & <Contained ag>_msdb. If you connect to a Contained AG Listener you will see this Databases as master & msdb

Request / Questions:

Is this a known limitation in Veeam Backup & Replication v13 with contained Always On Availability Groups?
Is there a documented workaround or supported solution to back up contained AG system databases using the SQL Plug-In or Agent?
If it is currently unsupported, is there a planned enhancement or patch to allow Veeam backups of these contained AG system databases?
Is it possible to exclude <Contained ag>_master from the backup prerequisites in a supported way without impacting the rest of the AG backup?
Logs and screenshots can be provided with the case if needed.