Common Backup Failures and Performance Issues


Reference article to consolidate information and provide troubleshooting steps for backup failures and performance issues.


Backups are taking a long time to complete or are failing.


What can cause a backup to fail with "The database update failed" or similar?
This error generally means that the backup appliance was unable to complete the database update for the backup. This more often than not is a secondary error to the actual root cause:

  • Check further up or down the error log in the UI for other errors. 

What can cause a backup to fail with "FATAL: Incomplete backup received from client."?

This error generally means that the backup appliance was unable to communicate with the Unitrends agent during the backup. Some items to check would be:

  • Has the IP address of the client changed?
  • Is the cabling between the client and the network plugged in? (Try a "ping" command from the client to the Unitrends backup appliance IP address)
  • Did the client reboot during the backup, perhaps due to a Windows update? (You can check this by looking at the Windows system event lot for reboot events during the time of the backup)
  • Does your firewall allow communication over the backup ports? For a list of backup ports see What ports need to be open for the Unitrends system?
For more detailed information on troubleshooting windows backup errors see General troubleshooting for Windows backup errors
What can cause snapshot related errors like "USNAPError! Writer has failed PrepareBackup request"?
  • For Windows application backups, the Microsoft VSS agents are invoked during the backup. Please check the Windows Application Event log. The Unitrends agent reports major backup information events, warnings, and messages.
  • If VSS errors are confirmed, restart the VSS service or reboot the client to reset VSS.
  • Check to ensure that you have sufficient free disk space on the volume that is failing. A general guide is 10% free space for snapshotting.
  • If the application is SQL Server, additional information can be found in Unitrends VSS SQL agent errors and warning messages
For more detailed information on USNAP errors see USNAP is not able to create a volume shadow copy
What can cause "Change Journal for volume C:/ appears to have wrapped since the last backup and will not be used for this backup." Messages?
    What can cause the "Host appears to be up, but had a network related error?" messages?
        What can cause warnings about files being skipped in backups (yellow backup status)?
          Also see the following Unitrends knowledge articles:



          For more information to alleviate slow backup performance, see the following KB articles:

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