Agentless backup for VMware VM fails if CD/DVD device of VM is connected to an ISO image which resides on a disconnected NFS datastore

Symptom

Perform the following steps to observe the issue:

1. Prepare an ISO image on a NFS datatsore connected to the ESX host.
2. Attach the ISO image to the CD/DVD device of a VM.
3. Disconnect the NFS datastore from network.
4. Perform agentless backup for the VM.

In this case, backup job fails with error message such as “Could not take snapshot of the virtual machine. ESX Server/vCenter Server reported the following error: A general system Error occurred."

Solution

Due to the limitation of ESX snapshot cannot be taken when VM disconnects the attached ISO image attached. As a workaround, detach the ISO image from the CD/DVD device of the VM before backup.