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

Question

I have an ASP.NET Web Api solution which doesn't contain a Startup.cs class. I presume this is because the solution wasn't created as an MVC solution.

All the code for the startup is defined in the Global.asax.cs file as you can see below

public class Global : HttpApplication
{
    void Application_Start(object sender, EventArgs e)
    {
        // Code that runs on application startup
        AreaRegistration.RegisterAllAreas();
        GlobalConfiguration.Configure(WebApiConfig.Register);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
    }
}

However, now I want to have support for OAuth and all the documentation that I've found is based on a Startup.cs with the following class

public partial class Startup
{
    public void Configuration(IAppBuilder app)
    {
        ConfigureAuth(app);
    }
}

Is it possible to just add this new class in my solution and the solution will continue working?

Will this have any conflicts with the Global.asax.cs class?

EDIT: After I added the Startup.cs class, I can't hit the break point I added into it...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.Owin;
using Owin;

[assembly: OwinStartup(typeof(MyGame.Startup))]

namespace MyGame
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            ConfigureAuth(app);
        }
    }
}

Any idea what's going on?

make sure you have added [assembly: OwinStartup(typeof(AuthorizationServer.Startup))] this above the startup class — Curiousdev
– Curiousdev, Commented Mar 28, 2017 at 17:50
I added it but still doesn't hit the breakpoint when I run the application. — user3587624
– user3587624, Commented Mar 28, 2017 at 22:02
My issue went gone when I added a reference to Microsoft.Owin.Host.SystemWeb in my solution. — user3587624
– user3587624, Commented Nov 21, 2017 at 19:51

freedeveloper · Accepted Answer · 2017-10-22 03:48:36Z

53

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

answered Oct 22, 2017 at 3:48

freedeveloper

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2 Comments

Adam W Over a year ago

This is correct answer for VS 2015 - It will generate all the necessary code for you.

uriz Over a year ago

make sure you have Microsoft.Owin.Host.SystemWeb nuget pkg installed. otherwise it will not work

General Grievance · Accepted Answer · 2020-03-18 13:53:42Z

47

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.

edited Mar 18, 2020 at 13:53

General Grievance

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answered Mar 28, 2017 at 17:40

Tyler Stahlhuth

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10 Comments

user3587624 Over a year ago

Actually, I added the Startup.cs and the Startup.Auth.cs and it is not breaking in the ConfigurAuth(app) line at all. I added the assemble ([assembly: OwinStartup(typeof(MyGames.Startup))]) above the namespace... Any ideas?

Tyler Stahlhuth Over a year ago

Did you install the package from NuGet?

user3587624 Over a year ago

I did. I have installed this: <package id="Microsoft.Owin.Security.OAuth" version="3.0.1" targetFramework="net46" /> but also many others like Jwt, Active Directory, etc...

Tyler Stahlhuth Over a year ago

Do you have <add key="owin:AutomaticAppStartup" value="true" /> under <appSettings> in web.config?

user3587624 Over a year ago

Just to add here that the issue went gone after adding a reference to Microsoft.Owin.Host.SystemWeb

|

Antonio Correia · Accepted Answer · 2019-02-15 01:58:36Z

5

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

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

edited Feb 15, 2019 at 1:58

Antonio Correia

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answered Aug 27, 2018 at 5:46

Peter J

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2 Comments

dylanT Over a year ago

Thanks for this. Spent all day trying to work this out and this was the answer.

Darth Scitus Over a year ago

This was it for me as well.

Laurenz Albe · Accepted Answer · 2019-09-04 14:17:27Z

2

Yes. first you need to remove the following line from your web.config.

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

Only then it will call the the method it startup.cs.

edited Sep 4, 2019 at 14:17

Laurenz Albe

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answered Sep 4, 2019 at 13:58

Jawahar

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2 Comments

Jason Over a year ago

This looks like a bit of a non-answer on an old question.

Laurenz Albe Over a year ago

@Jason the actual code was hidden because of missing formatting.

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