with Windows Server 2016 we introduced VHD Sets to create a shared virtual disk to be used with guest clusters. We also introduced production checkpoints to create application consistent backups.
Recently, I worked on a case where this may fail, and would like to share the Error codes and their reason:
Error code: '32768'. Failed to create checkpoint on collection 'Hyper-V Collection'
Reason: We failed to query the cluster service inside the Guest VM. Check that cluster feature is installed and running.
Error code: '32770'. Active-active access is not supported for the shared VHDX in VM group
Reason: The VHD Set disk is used as a Cluster Shared Volume. This cannot be checkpointed
Error code: '32775'. More than one VM claimed to be the owner of shared VHDX in VM group 'Hyper-V Collection'
Reason: Actually we test if the VHDS is used by exactly one owner. So having 0 owner also creates this error. The reason was that the shared drive was offline in the guest cluster
Hope this helps you to identify backup problems easier.