Dear all,
does anyone finally find out on how to fix this issue:
VSS writers inside virtual machine 'CONTOSO' failed to perform BackupComplete to its shadow copy (VSS snapshot) set: Catastrophic failure (0x8000FFFF). (Virtual machine ID 9851BE14-F276-459D-8D60-DF73B67EB658)
Our Hyper-V CSV hosted on NetApp storage, so we also unable to set-up proper back-up of VMs which is located at NetApp CSV.
All the VMs which is hosted on local hard drives of the host have no such issue with back-up.