The VM was reverted most likely to an earlier snapshot before the backup was performed.
This error applies to PHD Virtual Backup for VMware
This error can be due to a number of reasons, most likely though, the VM was reverted to an earlier snapshot before the backup was performed.
If a VM is reverted to an earlier snapshot, the change ID will no longer match when compared to previous available information. When this situation is encountered, a regular non-CBT backup will be performed. All backups after that will be performed with CBT enabled.
The following is a sample phdvb.log message that relates to this issue:
ubuntu-desktop[scsi0:0]: Could not get changed data. Current change UUID [52 cf 24 39 ef 06 8d 6c-b1 90 39 ca ca d9 3c 5e] is not equal to previous change UUID [52 24 4c 77 87 5e 64 8c-f6 ee 03 15 27 11 46 43]; This may be due to either reverting the VM to an earlier snapshot or for another reason. Continuing with a non-CBT backup.