Windows Volume Shadow copy Services (VSS) Problem Determination



Diagnostic Information for Microsoft Assistance

How to perform a VSS trace

VSS Writer Failed / How to Restart and Re-Register VSS Writers

Windows 2003 Hot Fixes

VSS Errors

VSS_E_BAD_STATE (0x80042301): A function call was made when the object was in an incorrect state. This indicates that Microsoft's VSS framework and/or perhaps some of the VSS writers are in a bad state.
VSS_E_UNEXPECTED (0x80042302): A volume shadow copy service (VSS) component encountered an unexpected error.
VSS_E_PROVIDER_NOT_REGISTERED (0x80042304): The volume shadow copy provider is not registered in the system.
VSS_E_PROVIDER_VETO (0x80042306): The shadow copy provider had an error. The provider was unable to perform the request at this time. This can be a transient problem. It is recommended to wait ten minutes and try again, up to three times.
VSS_E_PROVIDER_IN_USE (0x80042307): The shadow copy provider is currently in use and cannot be unregistered.
VSS_E_OBJECT_NOT_FOUND (0x80042308): The specified object was not found. This error means that Microsoft VSS failed to take a snapshot of your file systems and that the backup job will be unable to backup any files that are opened exclusively by other applications. The most common cause of this error is that VSS has been disabled on one or more of the volumes that are part of the backup.
VSS_S_ASYNC_PENDING (0x00042309): The asynchronous operation is pending.
VSS_S_ASYNC_FINISHED (0x0004230A): The asynchronous operation has completed.
VSS_S_ASYNC_CANCELLED (0x0004230B): The asynchronous operation has been cancelled.
VSS_E_VOLUME_NOT_SUPPORTED (0x8004230C): Shadow copying the specified volume is not supported.
VSS_E_VOLUME_NOT_SUPPORTED_BY_PROVIDER (0x8004230E):The given shadow copy provider does not support shadow copying the specified volume.
VSS_E_OBJECT_ALREADY_EXISTS (0x8004230D): The object already exists.
VSS_E_UNEXPECTED_PROVIDER_ERROR (0x8004230F): The shadow copy provider had an unexpected error while trying to process the specified operation.
VSS_E_CORRUPT_XML_DOCUMENT (0x80042310): The given XML document is invalid. It is either incorrectly-formed XML or it does not match the schema.
VSS_E_INVALID_XML_DOCUMENT(0x80042311): The given XML document is invalid. It is either incorrectly-formed XML or it does not match the schema.
VSS_E_MAXIMUM_NUMBER_OF_VOLUMES_REACHED (0x80042312): The maximum number of volumes for this operation has been reached.
VSS_E_FLUSH_WRITES_TIMEOUT (0x80042313): The shadow copy provider timed out while flushing data to the volume being shadow copied. This is probably due to excessive activity on the volume. Try again later when the volume is not being used so heavily.
VSS_E_HOLD_WRITES_TIMEOUT (0x80042314): The shadow copy provider timed out while holding writes to the volume being shadow copied. This is probably due to excessive activity on the volume by an application or a system service. Try again later when activity on the volume is reduced.
VSS_E_UNEXPECTED_WRITER_ERROR (0x80042315): VSS encountered problems while sending events to writers.
VSS_E_SNAPSHOT_SET_IN_PROGRESS (0x80042316): Another shadow copy creation is already in progress. Wait a few moments and try again.
VSS_E_MAXIMUM_NUMBER_OF_SNAPSHOTS_REACHED (0x80042317):The specified volume has already reached its maximum number of shadow copies. The volume has been added to the maximum number of shadow copy sets. The specified volume was not added to the shadow copy set. Other possible reasons: There is not enough free disk space on the drive where the locked file is located. Delete temporary files, empty recycle bin, etc. Fow WinXP, VSS has the limitation that only one shadow volume can be created per drive at a time. There could be another software that is already using the shadow volume for the drive. Restart your computer and try again.
VSS_E_WRITER_INFRASTRUCTURE (0x80042318): An error was detected in the VSS. The problem occurred while trying to contact VSS writers.
VSS_E_WRITER_NOT_RESPONDING (0x80042319): A writer did not respond to a GatherWriterStatus call. The writer might have terminated, or it might be stuck.
VSS_E_WRITER_ALREADY_SUBSCRIBED (0x8004231A): The writer has already successfully called the Subscribe function. It cannot call Subscribe multiple times.
VSS_E_UNSUPPORTED_CONTEXT (0x8004231B): The shadow copy provider does not support the specified shadow copy type.
VSS_E_VOLUME_IN_USE (0x8004231D): The specified shadow copy storage association is in use and so can't be deleted.
VSS_E_MAXIMUM_DIFFAREA_ASSOCIATIONS_REACHED (0x8004231E): Maximum number of shadow copy storage associations already reached.
VSS_E_INSUFFICIENT_STORAGE (0x8004231F): Insufficient storage available to create either the shadow copy storage file or other shadow copy data.
VSS_E_REBOOT_REQUIRED (0x80042327): A reboot is required after completing this operation.
VSS_E_VOLUME_NOT_LOCAL (0x8004232D): The volume being backed up is not mounted on the local host.
VSS_E_CLUSTER_TIMEOUT (0x8004232E): A timeout occurred while preparing a cluster shared volume for backup.
VSS_E_WRITERERROR_INCONSISTENTSNAPSHOT (0x800423F0): The shadow copy set only contains only a subset of the volumes needed to correctly backup the selected components of the writer.
VSS_E_WRITERERROR_OUTOFRESOURCES (0x800423F1): A resource allocation failed while processing this operation.
VSS_E_WRITERERROR_TIMEOUT (0x800423F2): The writer's timeout expired between the Freeze and Thaw events.
VSS_E_WRITERERROR_RETRYABLE (0x800423F3): The writer experienced a transient error. If the backup process is retried, the error might not reoccur.
VSS_E_WRITERERROR_NONRETRYABLE (0x800423F4): The writer experienced a non-transient error. If the backup process is retried, the error is likely to reoccur.
VSS_E_WRITERERROR_RECOVERY_FAILED (0x800423F5): The writer experienced an error while trying to recover the shadow copy volume.
VSS_E_LEGACY_PROVIDER (0x800423F7): This version of the hardware provider does not support this operation.
VSS_E_MISSING_DISK (0x800423F8): An expected disk did not arrive in the system.
VSS_E_MISSING_HIDDEN_VOLUME (0x800423F9): An expected hidden volume did not arrive in the system. Check the Application event log for more information.
VSS_E_MISSING_VOLUME (0x800423FA): An expected volume did not arrive in the system. Check the Application event log for more information.
VSS_E_DYNAMIC_DISK_ERROR (0x800423FC): An error occurred in processing the dynamic disks involved in the operation.
VSS_E_CLUSTER_ERROR (0x80042400): The clustered disks could not be enumerated or could not be put into cluster maintenance mode. Check the System event log for cluster related events and the Application event log for VSS related events.
VSS_E_UNSELECTED_VOLUME (0x8004232A): The requested operation would overwrite a volume that is not explicitly selected. For more information, check the Application event log.
VSS_E_SNAPSHOT_NOT_IN_SET (0x8004232B): The shadow copy ID was not found in the backup components document for the shadow copy set.
VSS_E_NESTED_VOLUME_LIMIT (0x8004232C):The specified volume is nested too deeply to participate in the VSS operation.
VSS_E_NOT_SUPPORTED (0x8004232F): The requested operation is not supported.
VSS_E_WRITERERROR_PARTIAL_FAILURE (0x80042336): The writer experienced a partial failure. Check the component level error state for more information.
VSS_E_WRITER_STATUS_NOT_AVAILABLE (0x80042409): Writer status is not available for one or more writers. A writer might have reached the limit to the number of available backup-restore session states.
VSS_E_KEY_DELETED (0x800703fa), Illegal operation attempted on a registry key that has been marked for deletion.



Sometimes just simple steps like the following will help to resolve issues with writers:

  1. Completely stop VSS SQL Writer Service
  2. Stop VSS Service
  3. Wait 10-15 sec
  4. Start VSS Service
  5. Start VSS SQL Writer Service
  6. Run command "vssadmin list writers"
  7. Verify, if any errors related to writer
  8. In case of errors check System and Application Events Log and see VSS and VSS SQL Writer error events and warning for more information

For additional troubleshooting steps, see also:

VSS Writer Failed / How to Restart and Re-Register VSS Writers

Windows 2003 Hot Fixes

Microsoft recommends the installation of hotfixes (QFEs) 833167 and 887827 for Windows 2003 VSS problems. Customers must contact Microsoft directly and request these fixes. Microsoft VSS Tuning Recommendations.

Controlling the VSS diff area size:

If after applying these fixes, one of the following events occurs:

  • "The shadow copy of volume C: took too long to install"
  • "The shadow copy of volume C: was aborted because the diff area file could not grow in time."

Consider reducing the I/O load on this system to avoid this problem in the future. If these events still occur, then the following registry key can be used to control the size of the diff area used by VSS:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VolSnap\MinDiffAreaFileSize : REG_DWORD :

(the default size is 300, you can increase it up to 3000)

Recommended event log maximum size: Microsoft indicates if the event logs are sufficiently large, the copy operation can take longer than the timeout for systems with high I/O load or high memory load. Microsoft recommends that Event logs are kept below 64MB in size.

Diagnostic Information for Microsoft Assistance

When it is determined that the VSS failure is outside the scope of Unitrends windows client, then the following information should be gathered for Microsoft support to examine:

  1. Windows application event log
  2. Windows system event log
  3. VSS trace (see instructions below)

Event logs:

Examine the application and system event logs focusing on the error events created by the VolSnap and VSS sources at the time of failure. It is helpful to extract the germane events from the log to isolate the problem and have a more productive interaction with MS support.

How to perform a VSS trace:

  1. Create a file tracefile.reg using the contents shown below and change the TraceFile entry to point to a volume that is not going to be shadow copied. Note the double backslash delimiter usage-you need to enter "\\" as the delimiter for each backslash in the path you wish to specify.
  2. Install tracing.reg.
  3. Reproduce the problem.
  4. Turn off tracing by deleting the key "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Debug\Tracing"

Here are the contents of the tracefile.reg registry file:

"TraceFile"="c:\\trace.txt" "TraceLevel"=dword:ffffffff "TraceEnterExit"=dword:00000001 
"TraceToFile"=dword:00000001 "TraceToDebugger"=dword:00000000 
"TraceFileLineInfo"=dword:00000001 "TraceForceFlush"=dword:00000000

I/O performance diagnosis:

Use Microsoft I/O performance tools to gather data for analysis. Check disk defragmentation. Checking health of writers Unitrends windows agent uses the VSS interface to read SQL data from the disk. If there is a problem with the VSS SQL writer responsible for SQL, use the Microsoft utility vssadmin.exe to ensure that the SQL writer is available on the system if a problem is suspected.


For more information see this Microsoft KB "Registry Keys and Values for Backup and Restore".

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