C# – Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug

Update: A sample project reproducing this bug can be found here at Microsoft Connect. I have also tested and verified that the solution given in the accepted answer below works on that sample project. If this solution doesn't work for you, you are probably having a different issue (which belongs in a separate question).

This is a question asked before, both here on Stack Overflow and other places, but none of the suggestions I've found this far have helped me, so I just have to try asking a new question.

Scenario: I have a simple Windows Forms application (C#, .NET 4.0, Visual Studio 2010). It has a couple of base forms that most other forms inherit from, it uses Entity Framework (and POCO classes) for database access. Nothing fancy, no multi-threading or anything.

Problem: All was fine for a while. Then, all out of the blue, Visual Studio failed to build when I was about to launch the application. I got the warning "Unable to delete file '…bin\Debug\[ProjectName].exe'. Access to the path '…bin\Debug\[ProjectName].exe' is denied." and the error "Unable to copy file 'obj\x86\Debug\[ProjectName].exe' to 'bin\Debug\[ProjectName].exe'. The process cannot access the file 'bin\Debug\[ProjectName].exe' because it is being used by another process." (I get both the warning and the error when running Rebuild, but only the error when running Build – don't think that is relevant?)

I understand perfectly fine what the warning and error message says: Visual Studio is obviously trying to overwrite the exe-file while it at the same time has a lock on it for some reason. However, this doesn't help me find a solution to the problem… The only thing I've found working is to shut down Visual Studio and start it again. Building and launching then work, until I make a change in some of the forms, then I have the same problem again and have to restart… Quite frustrating!

As I mentioned above, this seems to be a known problem, so there are lots of suggested solutions. I'll just list what I've already tried here, so people know what to skip:

• Creating a new clean solution and just copy the files from the old solution.

• Adding the following to the following to the project's pre-build event:

   if exist "$(TargetPath).locked" del "$(TargetPath).locked"
      if not exist "$(TargetPath).locked" if exist "$(TargetPath)" move "$(TargetPath)" "$(TargetPath).locked"
  

• Adding the following to the project properties (.csproj file):

   <GenerateResourceNeverLockTypeAssemblies>true</GenerateResourceNeverLockTypeAssemblies>
  

However, none of them worked for me, so you can probably see why I'm starting to get a bit frustrated. I don't know where else to look, so I hope somebody has something to give me! Is this a bug in VS, and if so is there a patch? Or has I done something wrong, do I have a circular reference or similar, and if so how could I find out?

Any suggestions are highly appreciated 🙂

Update: As mentioned in the comment below, I've also checked using Process Explorer that it actually is Visual Studio that is locking the file.