Predefined type 'System.Object' is not defined or imported .net 4.6

Question

I\'m using MVC 5 and .net 4.6 to create a web API that my mobile app can connect too.

Whenever I build the project I get hundreds of errors telling me that I need to add

Answer 1

I'm guessing a bit here but it looks suspicious that you are using the regular System.Data.* stuff for dnx451 but doesn't have anything to make up for it for dnxcore50. Are you targeting the core edition as well or is it just leftovers from project creation? If you want to target the core edition and still use the old System.Data.* stuff you'll need to wrap anything from those assemblies like this.

#if DNX451
// Do some DNX451 specific stuff here
#endif

And the other way around as well.

#if DNXCORE50
// Do some DNXCORE50 specific stuff here
#endif

But if you aren't thinking about supporting this yet I would simply remove dnxcore50 from the framework list and your errors will probably go away.