SUMMARY
Exception in virtual disk changes, a CBT issue.
ISSUE
If a SAN or host involved on a replication job crashes, the affected VMs could have untracked changes. ReliableDR will try to find the last CBT registered so the replication job may fail.
The replication job will be fixed activating the full replica option from Virtual machines tab.
More information about CBT could be found on this VMware article.
In some cases, such as a power failure or hard shutdown while virtual machines are powered on, CBT might reset and lose track of incremental changes.
Regardless of all if the CBT is corrupt you have to Reset CBT, see the CBT reset entry on this knowledge forum.