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What causes the "error opening mutex" error in Backup Pro 9 when accessing my AAG replica?

I'm running SQL server 2017 with RG Backup Pro 9 on Win Server 2016. On Friday I installed the server components on both nodes, from a 3rd server, with no issues and separate users. On Monday from that same 3rd server I get this error when attempting to access the secondary replica, primary is fine. Anyone run across this and if so how did you resolve it? The Back up agents are running fine with correct permissions for each so not clear what I should be looking for next. Any insights appreciated, Vince

Best Answer

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    Dan BDan B Posts: 287 Gold 5
    Hi VinceJ,

    Thanks for posting on the redgate forums.

    Taken from this page https://documentation.red-gate.com/sbu10/errors-and-warnings/sql-backup-errors-500-5292

    The initial diagnostics steps are below, please do let me know how you get on with this.

    Error acquiring mutex: <value>

    A mutex is a communication channel between SQL Backup Pro and the SQL Server processes. In certain circumstances a mutex can become orphaned. When SQL Backup Pro attempts to create a new mutex, the request will be rejected by Windows because a mutex of the same name already exists.

    Rebooting the operating system should resolve this problem. Alternatively, use Process Explorer to identify the process which is causing the problem:

    1. Download Process Explorer from http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx and run it.
    2. On the Find menu click Find Handle or DLL to open the Process Explorer Search dialog box.
    3. Type SQBMutex into the Handle or DLL substring box and click Search.
    4. For a SQL Server instance that is functioning correctly, the handles \BaseNamedObjects\SQBMutex_ and \BaseNamedObjects\SQBMutex_data_ will exist as part of the process SQBCoreService.exe (the SQL Backup Agent). For instances other than the default, the instance name will be appended to the handle (e.g. \BaseNamedObjects\SQBMutex_SQL2005).
    5. Select the problematic instance from the list to highlight the entry in the Process Explorer main window.
    6. Right click this entry and select Close Handle. repeat this for the corresponding data handle.

    You should now be able to start the SQL Backup Agent service and connect to the server.

    Kind regards,
    Dan Bainbridge
    Product Support Engineer | Redgate Software


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