When performing a VMware ESXi backup job following warning is shown in the backup log:
|*||erro||YYYY/MM/DD hh:mm:ss||Skip update from backup source "$guestVM$". Reason = "UUID conflict on Virtual Machine. "$guestVM$""|
The "UUID conflict on Virtual Machine." error is returned by the VMware host.
This indicates there is another guest virtual machine with duplicate UUID running on this VMware host. This situation could arise if the guest virtual machine was copied or cloned from another VMware host or datastore. VMware cannot run guest virtual machines with duplicate UUID's on the same VMware host
Please refer to these instruction on how to resolve the problem
UUID, copied, cloned, VMware ESXi, duplicate