Error acquiring mutex occurring during use

Category: Troubleshooting & error messages
Date: 30 Jan 2009
Product: SQL Backup
SQL Backup may encounter an error when trying to connect to a database server, either when performing an operation through the SQL Backup console or from a scheduled backup or using the extended stored procedure:

error acquiring mutex

Certain circumstances can cause a mutex, which is a communication channel between SQL Backup and the SQL Server processes, to become orphaned. When SQL Backup attempts to create a new mutex, the request is rejected by Windows because a mutex of the same name already exists.

A reboot should generally fix this issue, if this is an option.

The workaround is the following :

Using the tool "Process Explorer" from SysInternals (available from http://www.microsoft.com/technet/sysinternals/utilities/processexplorer.mspx)
* Click "Find", then "Find Handle or DLL"
* In the box, type "SQBMutex" (without the quotes), and click Search.
This should show the following:
For an instance that is functioning correctly, the handle "\BaseNamedObjects\SQBMutex_" and "\BaseNamedObjects\SQBMutex_data_" will exist, and be part of the process called "SQBCoreService.exe" (the SQL Backup Agent).
If the instance is not the default one, these names will be appended with the name of the instance (e.g. "SQBMutex_SQL2005")
For the problematic instance, click on the entry in the list (which will likely be linked to "sqlservr.exe" or similar), which will highlight the entry in the main window. Right click this entry and select "Close Handle". Repeat this for the corresponding 'data' handle as well.
You should now be able to start the SQL Backup Agent and connect to the server.