Backup of a SQL Server may fail with a VSS error.

From the log, the following message can be found:

One or more errors occurred. ---> Replay.Core.Contracts.Transfer.VssGeneralErrorException: There was a problem with the VSS subsystem on '(agent-machine)l'. ---> Replay.Agent.Contracts.ShadowCopy.ShadowCopyWriterFailedException: The VSS writer 'SqlServerWriter' failed during the 'DoSnapshotSet' phase with error WriterErrorNonRetryable. The VSS writer state is FailedAtPrepareSnapshot ---> Replay.Common.Contracts.ReplayException

In the Application event log on the machine, event 8229 is logged:

Event 8229
A VSS writer has rejected an event with error 0x800423f4, The writer experienc  ...