Visual Studio 2010 Build Fails to File Copy Error

visual-studio-2010 build copy file-locking
Antti Simonen picture Antti Simonen · Feb 2, 2012 · Viewed 10.1k times · Source

I'm building a project in Visual Studio 2010 and the build fails because it cannot copy the assemblyname.dll file from obj to bin folder. The exact error message is:

Error 7 Unable to copy file "obj\Debug\AssemblyName.dll" to "bin\AssemblyName.dll". The requested operation cannot be performed on a file with a user-mapped section open.

I think this is because the previous file in bin-folder is not accessible. When I try to delete the file manually, I get an error "The action can't be completed because the file is open in another program". If I try to see what application locks the file with Unlocker, I don't get any results (No Locking handle found).

If I restart Visual Studio, the error goes away but happens again after a build or two. Goes without saying that this is seriously slowing me down. Any advice how to start solving this?

Answer

Juha Palomäki picture Juha Palomäki · Jun 7, 2013

VIsual Studio 2012 on Windows 8. I was receiving the same error message on my project. Restarting Visual Studio or cleaning the obj folder manually did not help. Finally I closed all open files (Windows -> Close All Documents) and the problem went away.

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