Working with 2 Visual Studio 2015 instances : error CS2012 "file is being used by another process"

Question

With Visual Studio 2013, I used to open 2 instances of Visual Studio :

• one for a "server" solution (say a WCF host),
• one for a "client" solution (say a WPF app).

The 2 solutions have a common project, but this was not an issue : I could start the first in debug mode, start the second in debug mode, find a bug, stop one to fix the bug, and start it again (without stopping the second).

This scenario is no more possible with VS2015 : when I stop-fix-start one, I get a build error on the common project :

error CS2012: Cannot open 'D:\MyProject\obj\Debug\myCommonLib.dll' for writing -- 
'The process cannot access the file 'D:\MyProject\obj\Debug\myCommonLib.dll' because it is being used by another process.'

Is there a way to configure this error as "non blocking" for visual studio 2015 OR to go back to the vs2013 behavior ?

EDIT

Process explorer shows this handles when the client app is started :

• On VS2013 :

• On VS2015 :

==> we can show here 2 more handles on dll in the "obj" folder. This seems to be the problem.

Answer 1

From VS configure a new buid type for the project, this need to be configured the same as the Debug mode. Then run one of them in "Debug" and the other one in "Debug 2".

I hope these picture-guide could help you.