1466 - Error: Could not prepare for snapshot creation ... failed at prepare snapshot

Symptom

A backup fails with the following error:

Could not prepare for snapshot creation (VSS writer in an unexpected state): writer error 
(not retryable), please check the event log for related events from the application hosting 
the VSS writer (0x800423f4); 'failed at prepare snapshot' [Writer Name: 'SqlServerWriter', 
Writer ID: 'a65faa63-5ea8-4ebc-9dbd-a0c4db26912a'

Cause

The error message "VSS writer (0x800423f4); 'failed at prepare snapshot'" is related to the Volume Shadow Copy Service (VSS) in Windows. This error typically indicates that there was an issue during the preparation of a snapshot for a backup or restore operation.

Solution

Here are some troubleshooting steps you can take to address this issue:

1. Restart the Volume Shadow Copy Service:

• Open the Services console (services.msc).
• Locate the Volume Shadow Copy Service.
• Right-click on the service and select Restart.

2. Check the status of the VSS writers:

• Open a Command Prompt as an administrator.
• Type "vssadmin list writers" and press Enter.
• Check for any writers that are in a failed state, and note their name/s.
• If any writers are in a failed state, try restarting the associated service or rebooting the system.

3. Check available disk space:

• Make sure there is enough free space on the drive where you are trying to create the snapshot. You may need to change the location of the VSS snapshot in Windows using the steps below.

4. Check for backup software conflicts:

• If you have any other backup software installed, try disabling it temporarily to see if that resolves the issue.

5. Check the system event logs for additional error messages related to VSS.

If none of the above works, restart the server or workstation.

How to change the location of a VSS snapshot

To change the location of a VSS snapshot in Windows, follow these steps:

1. Open the Disk Management tool by right-clicking on Computer or This PC and selecting Manage, then selecting Disk Management under Storage in the menu on the left.
2. Right-click on the volume for which you want to change the snapshot location and select Properties.
3. Go to the Shadow Copies tab.
4. Select the snapshot for which you want to change the location and click on Settings.
5. Click on Change next to Storage Area.
6. Choose the new location where you want the snapshot to be saved, and click OK to save the changes.
7. Click OK to close the snapshot settings, then OK again to close the volume properties.

Note that changing the location of a VSS snapshot may affect the functionality of applications or services that rely on the snapshot, so it's recommended to do so only if necessary and after thoroughly testing the changes. Also, make sure that the new location has enough disk space to accommodate the snapshot.