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Barracuda Backup

How to Resolve Hyper-V Error During Backup Selection

  • Last updated on

 If you encounter an error during backup selection, you may have misconfigured or disabled Volume Shadow Copy Services (VSS) drivers. Use the following steps to help resolve the error.

Step 1. Review bbtrace.txt File

  1. Log in to the data source that is encountering the error, and go to the Backup Agent log files. By default, the log files are located in C:\Program Files\Barracuda\Barracuda Backup Agent\log

  2. Locate the file bbtrace.txt; this is the most recent log file.

    If the server was rebooted, or the agent was restarted, you may need to review older bbtrace.txt files to find the time listed in the Report details page in the previous step.

  3. Open bbtrace.txt in Notepad. This file contains data that is helpful in determining the specific error. Each log entry is time stamped, so you will first want to identify when the failed backup occurred based on the Report details page; note that there may be multiple days of log details so it is recommended that you use the search function to find the error.

    You may also see a failed to perform/create/open snapshot message following this error.


  4. Search the log file for terms such as Failed or Critical. Once you locate the term, review the associated content to determine the specific error message:
    07/23/15 23:07:07 0x0000b7c YVssManager: Bad writer status [Microsoft Hyper-V VSS Writer]: VSS_WS_FAILED_AT_PREPARE_SNAPSHOT

  5. In this example, a VSS snapshot failed during backup selection.
  6. Note the timestamp in the error, in this example:
    07/23/15 23:07:07
  7. Review your application and System event logs based on the error timestamp, for example 07/23/15 23:07:07, for any additional information about these errors to help resolve the problem.

Step 2. Check VSS Writers

  1. Open PowerShell.

  2. At the PowerShell command prompt, enter the following command:
    vssadmin list writers

  3. Determine if the Hyper-V VSS writer is in Stable condition. For example:
    C:\>vssadmin list writers
    Writer name: 'Microsoft Hyper-V VSS Writer'
    Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
    Writer Instance Id: {42422b7b-17aa-4cba-9241-0e34f8982f2f}
    State: [8] Failed last error: Retryable error

Step 3. Restart or Reboot

You can either restart the Hyper-V process or reboot the server and run a test backup or wait until the next scheduled backup runs.

If the problem persists, contact Barracuda Networks Technical Support.