Thanks for the help; this error has been resolved following the installation.
However, we have a new issue regarding CBT.
We are experiencing recurring CBT failures with the following configuration:
Veeam Backup & Replication: 13.1.1.18
Hypervisor: XCP-ng 8.3, three hosts
Identical packages on all hosts:
sm-3.2.12-25.1.xcpng8.3
blktap-3.55.5-11.1.xcpng8.3
xapi-core-26.1.19-1.1.xcpng8.3
These packages were installed on October 3, 2026, before the failures occurred.
Affected VM: NMNM-V-S-L007
Source disk UUID: 2f546ede-efcb-4ccf-8c23-2ea5a5e0d01f
Storage: LVM over iSCSI, SR name 70TB_HDD
SR UUID: 26d9572f-01c1-9cfd-79de-ca96eab601cf
The backup job finishes with a Warning. The failing operation is VDI.list_changed_blocks, which returns:
SR_BACKEND_FAILURE_460
Failed to calculate changed blocks for given VDIs.
[opterr=Source and target VDI are unrelated]
The logs show repeated failures on October 12 and 13, 2026. During cleanup of an older snapshot, CBT metadata is merged directly into the live disk despite the existence of a newer snapshot. This suggests a possible inconsistency in the CBT parent/child relationships, although the root cause has not been confirmed.
The reference snapshot used on October 13 was deleted only after the CBT failures, so its subsequent absence does not explain those failures.
Attached logs:
cbt-old-vdi-history.txt
cbt-source-disk-history.txt
cbt-chain-cleanup.txt
Please investigate CBT chain handling during snapshot creation and deletion, verify the installed Xen plug-in version, and advise whether a relevant hotfix or a supported procedure to re-establish CBT tracking is available.
Thank you.cbt-old-vdi-history.txt cbt-chain-cleanup.txt [cbt-source-disk-history.txt.zip](Invalid file type .zip. Allowed types are: .png, .jpg, .bmp, .txt, .diff, .patch, .jpeg)
