Since updating a project (4.x) to Unity 5.3, all my monodevelop classes have CS0103 errors

Unity Engine
1

All my classes have errors, even in the first lines of them…

The application still works, but none of the cross linking or features in monodevelop function at all…

For example, in the above code, the “MonoBehavior” is highlighted, and shows a CS0103 error: Monobehavior does not exist in the current context.

Did something significant change? Am i missing something?
Thanks

EDIT For some reason, deleting all files in the directory except my assets folder and project settings seems to have done the trick.

2

I’m not getting any errors when I paste your code into a script and add in a closing bracket.