SUMMARY
(VSS_E_WRITERERROR_RETRYABLE) The writer experienced a transient error. If the backup process is retried, the error may not reoccur.
ISSUE
Hyper-V backups fail with an error similar to:
GetWriterStatus: USNAPError! GatherWriterStatus call has returned a failure.
(VSS_E_WRITERERROR_RETRYABLE) The writer experienced a transient error. If the backup process is retried, the error may not reoccur.
Please check the Windows Event Log to ensure that Volume Shadow Copy Service and VSS Writers are operating properly. See also KB 000003650.
CreateVSSSnapshot: USNAPError! Writer has failed after PrepareBackup request.
Unitrends agent was not able to create Volume Shadow Copy.
To resolve this issue review the Event logs for any potential VSS errors and application specific Writer failures.
(VSS_E_WRITERERROR_RETRYABLE) The writer experienced a transient error. If the backup process is retried, the error may not reoccur.
Please check the Windows Event Log to ensure that Volume Shadow Copy Service and VSS Writers are operating properly. See also KB 000003650.
CreateVSSSnapshot: USNAPError! Writer has failed after PrepareBackup request.
Unitrends agent was not able to create Volume Shadow Copy.
To resolve this issue review the Event logs for any potential VSS errors and application specific Writer failures.
RESOLUTION
The (VSS_E_WRITERERROR_RETRYABLE) is generally caused by VSS in the Hyper-V host failing to create a snapshot. This in turn rolls out through Hyper-V integration services to VSS on the host and causes the Hyper-V writer to enter a failed state with the last error of retryable error. You can view details by typing "vssadmin list writers" at the command prompt of the host.
Writer name: 'Microsoft Hyper-V VSS Writer'
Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
Writer Instance Id: {c35d6ab0-9588-412f-ae7b-cdc37534501f}
State: [8] Failed
Last error: Retryable error
Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
Writer Instance Id: {c35d6ab0-9588-412f-ae7b-cdc37534501f}
State: [8] Failed
Last error: Retryable error
VSS on the host will often remain in this state until the host is rebooted or the related services are restarted. To correct this issue without rebooting the host type "net stop vmms" and once that completes type "net start vmms". If the condition persists, consult Microsoft's documentation for VSS.