Q:

Intellisense stops working (and references break) after compiling

I have a web app in my solution with a couple of c# classes.
I've added a win app to the same solution and I did add a reference to the Web app in the Win app application.
When I code in the Win app, the Intellisense gives me the Web app classes and properties and parameters.  It will even complain if the parameter types are not correct.  No problem.
But as soon as I build my Win app, I get a compile error that "The name 'MyWebClass' does not exist in the current context".
If it doesn't exist why is Intellisense smart enough to pick it up.  Perhaps that's why it is called INTELLIsense. 
What am I missing?

A:

This is common behavior when one assembly targets a certain framework version (say .NET 4.0), and another targets a different version (say .NET 4.5). Check your projects' properties and see if they are different. If they are, make them the same.

