No exports were found that match the constraint: ContractName

Hit this today trying to load a project.  Every project I fired up would throw this error when I tried to open any file! 

 

Turns out that the issue is a corrupted cache.  You just need to remove this directory

%AppData%\..\Local\Microsoft\VisualStudio\12.0\ComponentModelCache


Source
http://stackoverflow.com/questions/17596543/error-message-no-exports-were-found-that-match-the-constraint-contract-name