Changed Block Tracking (CBT) UUID Was Changed for Some Reason (code 1919)
A virtual machine backup plan terminates with the following info message: Could not apply the Changed Block Tracking feature. Changed Block Tracking (CBT) UUID was changed for some reason
The occurrence of this info message means that on a backup attempt a different Changed Block Tracking ID ( CBT UUID) was returned. Most likely, the virtual disks from the list were migrated, recreated, or overwritten between backup plan launches.
In other cases, other reasons are also possible.
However, the Changed Block Tracking was not applied to disks that returned changed CBT UUIDs which might cause the backup size growth.
Reset the Change Block Tracking for virtual machines that returned other UUIDs.
To learn how to do it, refer to the Resetting Changed Block Tracking for VMware vSphere virtual machines article at kb.vmware.com