Command copy exited with code 4 when building - Visual Studio restart solves it

Question

Every now and then when I build my solution here (with 7 projects in it) I get the dreaded \'Command copy exited with code 4\' error, in Visual Studio 2010 Premium ed.

Answer 1

I had the same error with xcopy in connection with the Test Engine. I am using VisualStudio Professional 2013. By default Test -> Test Settings -> Keep Test Execution Engine Running seems to be the reason for my error code 4 with xcopy. Switching it off solved the problem. The execution engine seems to keep hold on some .dlls.