The requested operation cannot be performed error when compiling an XNA project

Question

When compiling a project for the second time I get the following error message. I have to close down VS 2010 and it compiles when reloaded. If I make a change then the problem comes back.

"Unable to copy file "obj\x86\Debug\MyFile.dll". The requested operation cannot be performed on a file with user-mapped section open."

Answer 1

I had this problem for another cause. So I am sharing for those having this problem without the achievement extension

In my case, it was due to the project settings page being opened. I am using a type in my project as the type of one setting, so it appears that visual studio opens the dll to get the specs but don't release it automatically. Closing the settings page solve the problem or restarting visual studio.

Answer 2

Found cause - it's to do with having Visual Studio Achievements extension installed. The problem goes away with this extension removed.