Veeam and Hyper-V: Guest processing skipped (check guest OS VSS state and hypervisor integration components version)

With application-aware processing enabled in a Veeam backup job for a Hyper-V virtual server:

Guest processing skipped (check guest OS VSS state and hypervisor integration components version)
Failed to create snapshot (Microsoft Software Shadow Copy provider 1.0) (mode: Crash consistent) Details: Guest processing skipped (check guest OS VSS state and hypervisor integration components version)
Error: Guest processing skipped (check guest OS VSS state and hypervisor integration components version)

The reason is:

VM CAPTION IS #BACKUP USING SAVED STATE#. BACKUP WITH IN-GUEST VSS CURRENTLY IS NOT POSSIBLE

It seems that the Hyper-V integration components did not specify to use the system provider within this virtual server.  I forced using the  ‘Microsoft Software Shadow Copy provider’ inside the effected guest by adding this DWORD value.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\UseMicrosoftProvider = 1