Unable to copy file reference.dll to bin/reference.dll. The process cannot access the file reference.dll because it is being used by another process

Question

For one of my ASP.NET 3.5 applications, every single time I try to build the web app, it throws the following build errors in Visual Studio 2008:

Error 16

Answer 1

Use ProcessExplorer to find out what process has the file open and go from there.

If a process is currently using those DLL, you can't delete and re-write it. You'll have to kill or otherwise stop the process using those DLLs while you compile.