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

Try to use Package Manage Console and do

Update-Package Owin -Reinstall