Hi Ismail

Not sure if you've seen my reply on slack, but instead of overwriting UmbracoDefaultOwinStartup you can create a component and listen to the UmbracoDefaultOwinStartup.MiddlewareConfigured event. This event is fired when Umbraco is done configuring Owin

using Owin;
using Umbraco.Core.Composing;
using Umbraco.Web;
​
namespace Website
{
    public class MyComposer : ComponentComposer<MyComponent>, IUserComposer
    {
    }
​
    public class MyComponent : IComponent
    {
        public MyComponent()
        {
            // inject dependencies in the constructor
        }
​
        public void Initialize()
        {
            UmbracoDefaultOwinStartup.MiddlewareConfigured += (_, e) => ConfigureMiddleware(e.AppBuilder);
        }
​
        private void ConfigureMiddleware(IAppBuilder app)
        {
            // this is called when Umbraco is done configuring the Owin middleware
        }
​
        public void Terminate()
        {
        }
    }
}

It's AFAIK not possible to inject stuff into the OwinStartup class But looking at the UmbracoDefaultOwinStartup, ConfigureUmbracoAuthentication() is called right before the event is triggered https://github.com/umbraco/Umbraco-CMS/blob/8f32fce7818a556d4879e66851dbe91221c63fdc/src/Umbraco.Web/UmbracoDefaultOwinStartup.cs#L69 (the FinalizeMiddlewareConfiguration triggers the event)

So you should be able to run you're auth configuration in the ConfigureMiddleware method in the Component example shown above

is working on a reply...