Encountered an unexpected error when attempting to resolve tag helper directive '@addTagHelper'

Question

I\'m using Visual Studio 2015 Community edition, and I\'ve created an ASP.NET MVC 5 project.

When I open a view (Index of Home or any other), i

Answer 1

In my case it was the reference to System.Web.Mvc had disappeared.

There was lots of errors in the cshtml files but it would compile and run. Then I found that I had an error in the xxxcontrollers.cs file trying inherit controllers.

Seems it could compile because the dll was in bin already but it was giving errors.

I did not relish having to rebuild this project. That would be days and days.