Hyper-V Backup Job fails after 72 hours "Failed to call RPC function 'HvSetVmBackupStatus'"

A backup of a Hyper-V VM fails after 72 hours with the following error:
 

Failed to call RPC function 'HvSetVmBackupStatus': Snapshot with id '{snapshot-uuid}' was not found.

In the Task log for the specific VM ( %programdata%\Veeam\Backup\<jobname>\Task.<vmname>.<vm-uuid>.log ) the following error is found:
 

Error    The device is not ready. (Veeam.Backup.Common.CCppComponentException)
Error    Failed to read data from the file [\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy3\<foldername>\<vmname>\Virtual Hard Disks\<vmname>.vhdx]. (Veeam.Backup.Common.CCppComponentException)

In the Svc.VeeamHvIntegration.log log file found on the Veeam Backup & Replication server ( %programdata%\Veeam\Backup ) the following is found:
 

WARN|[GC] Removing expired  snapshot. Creation time: '<date-stamp>'. JobInfo: 'Locked Job [<jobname>], Backup console [<veeamservername>]'. Is successful snapshot: 'true'. Is completed: 'true'. Life time: '72' hour.

 

This failure occurs due to the Veeam Backup & Replication built-in 'snapshot life time' limit of 72 hours.
This limit is intended to prevent issues with performance due to a VM running on a shadow copy for extended periods of time.

Initial troubleshooting for this issue should be to investigate performance to determine if improvements can be made which will allow the backup of the VM to complete within the 72 hour limit.
 

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If it is not possible to improve performance, the 'snapshot life time' limit is adjustable with a registry entry on the Veeam Backup & Replication server:

(The Veeam Backup Service on the Veeam Backup & Replication server must be restarted after the key is modified to take immediate effect)

Location: HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication\
Type: DWORD
Name: hvSnapshotLifeTimeHour
Value (Default): 72

The value may be doubled or set to a value which is sufficient to allow the VM to complete being backed up.

It is inadvisable to set the value any higher than 240 unless absolutely necessary, and should never exceed 596. In most cases a value of 144 (double default) works well.