I've had this happen with my NuGet packages every once in a while. I haven't been able to identify exactly how it happens. (I assume user error.) I didn't need to upgrade anything to solve it, just clear the NuGet cache:

I use the nuget command line tool found here.

You can clear all caches with this command:

nuget locals all -clear

See: https://docs.nuget.org/consume/command-line-reference

You'll probably need to restart Visual Studio if it is open.

As per the best answer to the question....

• Update MVC package (Visual Studio > Right click project/solution > manage nuget packages > Updates > Microsoft ASP.NET MVC > Update)
• Manually add the compilation assembly

but then

• Find - System.Web.Mvc, Version=4.0.0.0
• and replace with - System.Web.Mvc, Version=4.0.0.1

Which will find all the hidden references in the Views/Web.config files.

Every time I have had this issue I always start by doing a rebuild which will clear your bin folder. You likely do not need to close and open visual studio, as I never have, and it should work.

If this doesn't work then try more complicated solutions like those above but this could be a quick, clean fix.