The type or namespace IAppBuilder could not be found(missing using a directive pr an assembly reference)

Question

I am working on an Asp.Net MVC 4 Application in which I am using SignalR 2.0.1 and I Mapped it using Owin Startup class and it worked fine at first.

All of a sudden

Answer 1

The IAppBuilder interface is found under Owin package. Just add a reference in your class file:

using Owin;

And rebuild. Your project will pick this up.

I have no idea why VS didn't pick this up, but it didn't. Once I added this reference to my project, then everything fell into place.