Many times we have backups, of Windows servers and VMs, fail because one or more VSS writers fail. The backup logs and event viewer would indicate that a VSS shadow copy operation failed for various reasons and this may leave the VSS writer in a Failed state as seen below

Many times a reboot may resolve the issue but obviously it is not always possible to restart the server, especially if there are a number of applications running on it or multiple virtual machines. Instead you may want to find the relevant service and restart it to try and refresh the state of the VSS writer.

To find the VSS writer that failed, you will need to open an elevated command prompt and execute the command:

vssadmin list writers

The console will list all the VSS writers installed/available in windows and among them you may find some with a failed state.

Writer name: 'Microsoft Hyper-V VSS Writer'
  Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
  Writer Instance Id: {b063f91d-4768-471e-9687-5b56f9c8bb30}
  State: [7] Failed
  Last error: No error

The above shows the ‘Microsoft Hyper-V VSS Writer” is in a failed state. To reset the VSS writer and you will need to restart the Hyper-V Virtual Machine Management service. Run the command again to ensure that the VSS writer is in a Stable  state

Writer name: 'Microsoft Hyper-V VSS Writer'
  Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
  Writer Instance Id: {b063f91d-4768-471e-9687-5b56f9c8bb30}
  State: [1] Stable
  Last error: No error

Note: This has fixed the issue for me on many occasions but sometimes you may need to re-register the VSS writers or you may be running out of disk space. It is important to check the Event log to understand better what is causing the VSS writer to fail. Sometimes there is no other way around it and you would need to restart the server or vm.

As you may know, there are more VSS writers that could fail. When this happens I end up Googleing to find the associated service to restart. To have them handy for myself and hopefully for anyone else that comes across this, below is a list of the VSS writers name and associated Service to restart.

I go the list from the Dell AppAsure KB129774 and willtry to update it if I find new ones.


VSS Writer Service Name Service Display Name
ASR Writer VSS Volume Shadow Copy
BITS Writer BITS Background Intelligent Transfer Service
COM+ REGDB Writer VSS Volume Shadow Copy
DFS Replication service writer DFSR DFS Replication
DHCP Jet Writer DHCPServer DHCP Server
FRS Writer NtFrs File Replication
FSRM writer srmsvc File Server Resource Manager
IIS Config Writer AppHostSvc Application Host Helper Service
IIS Metabase Writer IISADMIN IIS Admin Service
Microsoft Exchange Writer MSExchangeIS Microsoft Exchange Information Store
Microsoft Hyper-V VSS Writer vmms Hyper-V Virtual Machine Management
NTDS NTDS Active Directory Domain Services
OSearch VSS Writer OSearch Office SharePoint Server Search
OSearch14 VSS Writer OSearch14 SharePoint Server Search 14
Registry Writer VSS Volume Shadow Copy
Shadow Copy Optimization Writer VSS Volume Shadow Copy
SPSearch VSS Writer SPSearch Windows SharePoint Services Search
SPSearch4 VSS Writer SPSearch4 SharePoint Foundation Search V4
SqlServerWriter SQLWriter SQL Server VSS Writer
System Writer CryptSvc Cryptographic Services
TermServLicensing TermServLicensing Remote Desktop Licensing
WINS Jet Writer WINS Windows Internet Name Service (WINS)
WMI Writer Winmgmt Windows Management Instrumentation


Hope you found this useful. Let me know in the comments section!


By Brian Farrugia

I am the author of More info can be found on the about page.

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