BA4932: Hyper-V VSS consistency check failed¶
| Error code | Product | Applies to |
|---|---|---|
| BA4932 | BackupAssist | For BackupAssist 15.0.5 or later. |
Description¶
When a backup protects Hyper-V through VSS, BackupAssist detects the Hyper-V VSS writer while it plans the backup and again in the snapshot it actually takes. This condition is reported when the Hyper-V writer was present during planning but was not present in the backup snapshot, which means one or more guests may not have been captured in an application-consistent state.
Common causes:
- The Hyper-V VSS writer failed, timed out, or entered a bad state between planning and snapshot creation.
- The Volume Shadow Copy or Hyper-V Virtual Machine Management services were restarted (for example by a pre-backup script) while the job was running.
- The Hyper-V writer was excluded because a VSS-related service was not available (see BA615).
Resolution¶
Resolution 1 - Check and reset the Hyper-V VSS writer (recommended)¶
- From an elevated command prompt run "vssadmin list writers" and find Microsoft Hyper-V VSS Writer.
- If it is not shown as Stable / No error, restart the Hyper-V Virtual Machine Management (vmms) service to re-register the writer.
- Confirm the Volume Shadow Copy services are healthy (see error BA615) and that the affected guests are running normally.
- Run the backup again and confirm the condition no longer appears.
Resolution 2 - Avoid disrupting VSS during the backup¶
If a pre-backup script restarts VSS-related services, make sure they are running again before the backup proceeds. Review the Hyper-V-Worker and application event logs for VSS writer errors around the backup time.
Note on the backup report¶
This condition appears in the backup report as: Hyper-V VSS consistency check failed.
| Last updated | Created | Further assistance |
|---|---|---|
| 7th Aug 2026 | 7th Aug 2026 | BackupAssist Support page |