Unable to copy a file from obj\Debug to bin\Debug

Question

I have a project in C# and I get this error every time I try to compile the project:

(Unable to copy file \"obj\\Debug\\Project1.exe\" to \"bin\\Debug

Answer 1

We recently experienced this on a WinPhone 8 project, in VS 2012 Update 2.

Inexplicably, the cause was using the Tuple type. Removing the code that used a Tuple the problem went away. Add the code back the problem returned.