SIRIS, ALTO, and NAS: Resolving VSS Writer Errors in Windows 8, Server 2012, and Up



This article discusses how to attempt to repair failed VSS writers on a protected machine that is running Windows 8 and higher, Windows Server 2012, or higher.


  • Windows 8 and higher
  • Windows Server 2012 and higher


Datto appliances use the Volume Shadow Copy Service, also known as VSS Writers, to run backups. For more information about VSS Writers, check out SIRIS, ALTO, and NAS: VSS: Description, Compatibilities, and Troubleshooting Resources.

When VSS writers on Windows 8 or Windows Server 2012 fail, it could cause backups to fail. The process to repair VSS Writers usually involves using the VShadow utility, but this tool is not available for the above two operating systems. This article describes an alternative method. 

VSS Writers, Services and Processes

Below is a chart including the various VSS writers along with the associated process and service.

VSS Writer Process (.exe) Service
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
FRSM Writer srmsvc File Server Resource Manager
IIS Config Writer AppHostSvc Application Host Helper Service
IIS Metabase Writer IISADMIN IIS Admin Service
Microsoft Exchange Replica Writer MSExchangeRepl Microsoft Exchange Replication Service
Microsoft Exchange Writer MSExchangeIS Microsoft Exchange Information Store
Microsoft Hyper-V VSS Writer vmms Hyper-V Virtual Machine Management
MSMQ Writer MSMQ Message Queuing
MSSearch Service Writer WSearch Windows Search
NTDS NTDS Active Directory Domain Services
O_Search VSS Writer OSearch Office SharePoint Server Search
O_Search 14 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
WIDWriter WIDWriter Windows Internal Database VSS Writer
WINS Jet Writer WINS Windows Internet Name Service (WINS)
WMI Writer Winmgmt Windows Management Instrumentation

Repairing VSS Writers

The following steps are basic troubleshooting workflows for repairing VSS writers.

  1. On the target machine, open an elevated command prompt with administrator privileges.
  2. Run the command vssadmin list writers, and make a note of any writers in a Failed state.
  3. Open services.msc on the machine. Reference the above table, and stop the services for the VSS writers that have failed.
  4. Open task manager and hard kill the processes for the related failed VSS writers.
  5. Return to services.msc and restart the related services.
  6. Run vssadmin list writers again to make sure the VSS writers are now showing as stable.

It is imperative that all VSS writers be in a stable state on the protected machine. If any writers have failed, they can cause backups to fail.

NOTE: If following these steps does not repair the writers, even after a full reboot of the production machine, you will need to contact Microsoft, or review their articles in the Troubleshooting VSS Applications (external link) section of their Knowledge Base. Datto is unable to provide extended support for VSS writers, as they are a proprietary Windows application.

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