So Harry you are wrong. Imagine that I can load monogame.framework.dll assembly from 4.0 framework executable assembly. Moreover monodevelop 5.10 builds solution successfully and application works good. It’s a paradox. But visual studio does not build solution, it writes error that frameworks is mismatched. Therefore I’ve set a targeted framework 4.0 for monogame project and that exception is thrown after building for 4.0 framework.