you will get a very stupid error like this:
System.BadImageFormatException : Could not load file or assembly or one of its dependencies. An attempt was made to load a program with an incorrect format.
In my case, I was getting it in a TestFixtureSetUp method.
DUH. I had set the class library project to force to x86, because I’m on x64, but I wanted to use edit and continue. I never changed the Test project, so it was still running x64. It failed with a “BadImageFormatException” when it loaded the references x86 project.
Don’t be stupid like me.