Releasing Files In Use By Other Processes

When developing an application that uses a SQL Server Compact Edition database, you may run into a problem getting your application to build if you frequently compile it to test changes. Specifically the following error:

Problem generating manifest. The process cannot access the file ‘C:\…\mydb.sdf’ because it is being used by another process.

The problem is that your application didn’t properly release its lock on the SQLCE database file the last time you ran it. I find this especially happens when you’re debugging and hit an unhandled exception. Since your application runs as a child of the devenv.exe (Visual Studio) process, closing and reopening Visual Studio will release the lock on the SDF file and allow you to successfully compile again. Obviously, restarting Visual Studio everytime you want to test your application isn’t very convenient.

There is an easier solution to this problem. You’ll need to download Process Explorer, a free utility provided by Microsoft. According to the website, “Process Explorer shows you information about which handles and DLLs processes have opened or loaded”. This is precisely what we need to release the SDF file that Visual Studio has taken hostage.

So open up Process Explorer, and using the “Find Handle or DLL…” feature search for “sdf”. You may end up with several results, but what you’re looking for is the SDF that you use in your application. Once you find it, double click it. The file will then appear highlighted on the bottom half of the window, right click it and select “Close Handle”. The lock on the file will be destroyed, allowing you to successfully build your application without getting manifest generation errors.

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