Backup from virtual machine fails with VMOMI error. The issue occurs when you have an old hardware version of a virtual machine and it fails to back up when Auto-Enable CBT is selected in VM Backup Policy. The following entry is logged in the detailed backup job logs.
You can get the VM hardware version of the VM (vmx-04) from the Phoenix log file.
Upgrade the hardware version of the virtual machine to 7 or later. Virtual machine hardware version 7, introduced with vSphere 4.0, is the first version released that supports CBT.
If VM hardware upgrade is not possible, move the virtual machine to a different VM server group with a VM backup policy that has disabled the Auto enable CBT setting.