Challenge
Job will fail with the error Failed to call RPC function 'Vss.FinishSnapshot': Error code: 0x800401fd
In the guest helper logs you will see the below occur before Veeam sends the VSSControl: FinishSnapshot started command in the task log.
18/10/2018 22:39:41 2688 INFO RPC: KeepSnapshotEx. Ok.
18/10/2018 23:00:00 21004 WARN Snapshot timeout occurred.
Cause
Vss snapshot is timing out before Veeam is able to send the finish command.
Solution
Add the below key to the registry location “HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication\” on the Veeam server. After applying the key make sure no jobs are running and restart the Veeam backup service.
The default value is 1200 so attempt doubling that value when creating the key.
VSSGuestSnapshotTimeout
Type: REG_DWORD
Default value: 1200 (in seconds)
Description: Found in job log as "VSSControl: KeepSnapshot started, ttl 1200 sec". Registry setting was added in v9 update 1. Prior to that, this timeout was hard-coded to 600 seconds. This registry key goes to the Veeam Server