Assume that you use Microsoft SQL Server 2014 that has databases with memory-optimized objects. When you restart SQL Server, it restarts successfully, and you may occasionally receive the following messages in the error log:

[ERROR] Unable to delete file <File Path>\<File Name>.dll for reason 5. File renamed to <File Path>\<File Name>.old_dll. This issue may be due to a previous failure to unload memory optimized table DLLs.


The issue occurs because of a timing issue. On server restart for databases with memory-optimized objects, the server is sometimes unable to delete old DLLs for memory-optimized tables. The server can continue the restart by renaming the old DLLs. But it logs a message to the error log for which there is no user action required or possible.

Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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