MVC Razor view Intellisense broken in VS 2013/2015/2017

Question

I have an existing project written in VS2010 which when loaded in VS2010 works perfectly.

When I load this same project in VS2013 the MVC Razor views contain lots of

Answer 1

This question has been resolved, but I'm adding this for future folks, since none of the above worked for me:

Try running Visual Studio as an administrator.

Somehow when I tried to delete my nuget packages (which contain all the required references, such as System.Web.Mvc, I was told I need permission from MyPC\Me. Ridiculous! (I am the only user and only admin...) In any case, running as an admin at least let me access those files which fixed intellisense.