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When configuring a Microsoft SQL Server backup set, both of the following are true:

  • The list of databases does not appear in the "What would you like to back up?" section of the main Backup page.
  • The message "Internal error" appears above or below the area where the list of databases should appear.

What's going on?

ZCB uses the SQL VSS Writer to generate the list of databases to be backed up. The "Internal error" message is generated instead of a list of databases when the SQL VSS Writer is not available.


Open an elevated (run as administrator) command prompt and run the following command: vssadmin list writers

  • A list of VSS Writers will appear.
  • Verify that a writer named SQLServerWriter is included in this list.

 Click here to see example output from 'vssadmin list writers'

In this screenshot, the SQLServerWriter is properly listed:

In this screenshot, the SQLServerWriter is not listed at all:

If the SQL VSS Writer is not listed, action must be taken before it is possible to configure the Microsoft SQL Server backup set.

Begin by ensuring that all requirements for Microsoft SQL Server backups are met. Requirements are outlined in your User Guide, available at

Once all requirements are met, run the vssadmin list writers command again. If the SQL VSS Writer is still not listed, please refer to Troubleshooting SQL VSS Writer issues for further troubleshooting information.