During the Backup job for Lotus Domino server, I received the following error “Failed to create snapshot (Microsoft Software Shadow Copy Service Provider 1.0) (mode:Hyper-V child Partition Snapshot). Provider does not support shadow copies of volume . -tr: Failed to add volume to snapshot set. -tr Failed to perform pre-backup tasks”
Contacted Veeam support and suggested following steps
Do a “vssadmin list providers” and “vss admin list writers” on the host hosting Domino server right now to see if there are any failed VSS components(they all should be in status  Stable No Error. I can see a few customer cases with such error where host reboot and\or cluster re-add procedure to the Veeam console helped. So I would start with checking VSS, then re-add cluster to Veeam(Backup Infrastrcutre). If nothing helps, HV reboot.
First checked the VSS writers and Providers. all was ok and was in working status. then rebooted the Domino server and tried to back it up again, this time it didn’t receive any error and the backup job completed successfully without any errors or warnings.