Unable to generate delta using CBT., Reason = “[QueryRCTChanges][QueryChangesVirtualDisk] path= “******.AVHDX”, Error There is no change tracking data available associated with the specified change tracking identifier.rn”
We are unsure why this error occurred on what was a healthy backup where nothing had changed.
Hyper V wasn’t clustered and the customer was also using VEEAM which we were managing for them.
The VEEAM repository was backing up successfully to BOBcloud.
We requested the customer upgraded to v22.214.171.124
This resolved the issue.
The backup was failing on an AVHDX file and we suspect there was a locked-out transaction which was flushed when the new version of our software was installed. This had the effect of flushing previous transactions and restarting the VSS snapshot on the guest VHDX files.