DisconnectedContext error when running Unit Tests in debug in VS2015

I also have Rashaper and faced with this problem, no matter from where I am calling the tests (VS or Resharper). I've overcome this by changing the target architecture of the tests and the projects to the x64. But the source of the problem is still unknown for me.

Check if you set the compiler to "Release" instead of "Debug". That solved the issue for me!

I had this exception while debugging a WCF service in Visual Studio 2015. No usage of ReSharper. Changing the default architecture as suggested by shfire to X64 fixed it for me.

Because my project is a migrated Visual Studio 2012 project I compared the default processor architecture with the settings in VS2012. In VS2012 the default architecture isn't selected or selectable! I think this is a new bug and/or feature of VS2015 ;-)