XCP-NG backup failing - The snapshot chain is too long

[czopper]

1/30/2026 12:07:17 AM :: HVFS01 : Failed to perform backup: [TBD] Task a4cb9b82-3138-ea91-19d8-f152d2c21b92 (Async.VM.snapshot) failed: . SR_BACKEND_FAILURE_109. . The snapshot chain is too long.

Any thoughts on getting past this?

[Mildur]

Hi Richard,

As indicated in the error message, I would first delete the VM snapshots on Proxmox.
If that doesn’t help, please contact our support team.

Best,
Fabian

[cody.ault]

Based on the error, if you can't clear the snapshots, it might be worth reaching out to Vates to check on the health of the VM. We rely on checkpoints to take backups but they should be cleaned up. I can reach out to collect logs to see if we're seeing any error messages on the cleanup process on our side but the hypervisor vendor might be needed as well to cleanup the VM safely.

[czopper]

I deleted all of the snapshots (30) and ran the Veeam backup last night with the same results. There were over 40 new snapshots created and the backup job once again failed. Each snapshot had a duplicate copy.

[jmannik]

ive had a similar issue with both hyper-v and vmware as well as on XCP-NG.

Did you make sure the snapshots coaleced before kicking off the backup job?
That was the problem I had when I had this issue, the snapshots had not finished consolidating/coalesing

[cody.ault]

We have identified an issue in the beta around failed jobs and snapshots. When a job fails, the snapshot consolidation request doesn't happen until the next successful run. Since this has been failing for a little while, the snapshots have built up. Based on the logs, there was originally a low space issue that prevented the job from processing. We are still only adding one snapshot per job run to the disks however, so if you've cleared them and then still see a bunch of snapshots after the next run, then there might be something wrong with the manual deletion process.