BA4913: Exchange VSS consistency check failed¶
| Error code | Product | Applies to |
|---|---|---|
| BA4913 | BackupAssist | For BackupAssist 15.0.5 or later. |
Description¶
When a backup protects Microsoft Exchange through VSS, BackupAssist detects the Exchange VSS writer while it plans the backup and again in the snapshot it actually takes. This condition is reported when the Exchange writer was present during planning but was not present in the backup snapshot, which means the Exchange data may not have been captured in an application-consistent state.
Common causes:
- The Exchange VSS writer failed, timed out, or entered a bad state between planning and snapshot creation.
- The Volume Shadow Copy or Exchange services were restarted (for example by a pre-backup script) while the job was running.
- The Exchange writer was excluded because a VSS-related service was not available (see BA615).
Resolution¶
Resolution 1 - Check and reset the Exchange VSS writer (recommended)¶
- From an elevated command prompt run "vssadmin list writers" and find Microsoft Exchange Writer.
- If it is not shown as Stable / No error, restart the Microsoft Exchange Information Store service to re-register the writer.
- Confirm the Volume Shadow Copy services are healthy (see error BA615).
- 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 Exchange application event logs for VSS writer errors around the backup time.
Note on the backup report¶
This condition appears in the backup report as: Exchange VSS consistency check failed.
| Last updated | Created | Further assistance |
|---|---|---|
| 7th Aug 2026 | 7th Aug 2026 | BackupAssist Support page |