ASP.NET Web Api - Startup.cs doesn't exist

If you have installed the Owin packages, you can simple create the start up class with:

Startup.cs is a part of the OWIN authorization package. If the package isn't added through NuGet, I can't guarantee it would work. However, judging by this answer, it might work anyway depending on your environment.

https://stackoverflow.com/a/24678109/6442626

Short answer: If you installed Microsoft.Owin.Security.OAuth from NuGet, that should be good. Otherwise, you need to install it.

Update: In order to get MVC to call the Configuration method in startup, you also need to install the Microsoft.Owin.Host.SystemWeb package from NuGet. There is nothing special you need to change with web.config, IIS will automagically detect the Owin host and load it for you.

You can add your own startup class, but you need to make sure that Owin is recognizing it. There are several ways to do this , but if you'd like to use a Startup class then you need to use the OwinStartup attribute.

eg:

[assembly: OwinStartup(typeof(MyNamespace.MyStartupClass))]

My Startup.cs would not run until I removed this line on Web.config (in root folder)

<add key="owin:AutomaticAppStartup" value="false" />