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Article Summary: This article provides information on troubleshooting errors related to Volume Shadow Copy and Windows Server Backup. In all versions of Windows since Windows Server 2003, the native backup utility (Windows Server Backup, the successor to NTBackup) relies on the Volume Snapshot Service (VSS), also known as Volume Shadow Copy or simply Shadow Copy. Most third-party backup utilities for Windows also rely on this service, and backup-related problems are often caused by VSS issues. General Troubleshooting Disable all but one backup application. Running multiple backup applications on one server can cause conflicts.Restart the Volume Shadow Copy service from the Services console.Reboot the server when it is possible to do so.Disable and re-enable Volume Shadow Copy. Steps for doing so are given below.Search the Microsoft Support site for available hotfixes for VSS. Make sure they apply to the particular version of Windows running on the affected server. Repair VSS Issues in Windows Server 2003 Run the vssadmin list writers command to check the status of all VSS writers on the system.If any writers show errors, restart the VSS service and run vssadmin list writers again.If any writers still show errors, reboot the server.If the writers still show errors after a reboot, follow the steps in Microsoft Knowledgebase article KB940184 to re-register the DLL files associated with VSS.If the VSS writers show no errors, attempt to back up the server using the native NTBackup tool.If the backup still fails, look through the server's event logs for specific errors relating to VSS and research any relevant errors you find. Repair VSS Issues in Windows Server 2008 and LaterThe most important point to remember when troubleshooting VSS issues in Windows Server 2008 and later versions is that re-registering the associated DLL files is not recommended. It is still possible to do so, and there is scattered anecdotal evidence online that it occasionally works, but there is also a chance that it will fail and cause other issues that can only be resolved by completely reinstalling the operating system. For this reason, Microsoft advises against re-registration in KB940184. Review the information in Troubleshoot VSS Issues that Occur with Windows Server Backup (WBADMIN) in Windows Server 2008 and Windows Server 2008 R2.Use the vssadmin list writers, vssadmin list providers, and vssadmin list shadows commands to display the status of all VSS writers and providers in the system, as well as the list of existing shadow copies.If any VSS writers or providers show errors, restart the Volume Shadow Copy service and run the applicable command again.If any VSS writers or providers still show errors, reboot the server and run the applicable command again.Use the vssadmin delete shadows command to delete existing shadow copies.Search the server's event logs for relevant errors and research any that you find. For information on how VSS works, please see The Basics of the Volume Shadow Copy Service (VSS).The vssadmin command reference is available at the following Microsoft TechNet page: Vssadmin.

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