If you have already tried other workarounds to perform the backup successfully, the only last chance is to remove the VSS component on this dedicated VM.
How to remove the VSS component:
- right-click the VM and select “Guest” – “Install/Upgrade VMware Tools”
- select “Interactive Tools Upgrade”
- log-on to the virtual machine and start the VMware Tools Setup (you can start it via Explorer – DVD Drive)
- select “Custom”:
- deselect the “VSS Support” (Volume Shadow Copy Service Support)
- now finish the wizzard – done!