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InvalidOperationException: No authenticationScheme was specified, and there was no DefaultChallengeScheme found.

Sometimes, you have of these days where you stumble from one issue to another. This was (unfortunately) one of these days. The story started when I tried to run an ASP.NET Core project I had to review. (Always my first check, can I follow the instructions in the readme.md file and get the source code up and running easily on my local machine).

But this day, no luck, as ASP.NET Core decided to give me the following error message:

InvalidOperationException: No authenticationScheme was specified, and there was no DefaultChallengeScheme found.

Typically this indicates that no authentication is configured, but a look at the Program.cs file didn’t bring me closer to the solution. Everything looked okay:

Then I noticed the following in my Visual Studio, I was running the application through Kestrel.

Could that be the reason? I switched to IIS Express and ran the application again. Now I was able to start the application succesfully.

Enabling Windows Authentication for Kestrel

Does this mean that Windows authentication is not supported for Kestrel? Since ASP.NET Core 3.1 it is. Windows Authentication can be configured for ASP.NET Core apps hosted with IIS, Kestrel, or HTTP.sys.

Let’s see how to get this done.

First we need to install the Microsoft.AspNetCore.Authentication.Negotiate NuGet package. This package is required to support Windows Authentication with Kestrel.

We update our application bootstrapping logic to use this authentication package:

Next we need to update our launchsettings.json. We add an extra authenticationMode setting and set it to Windows.

If we now run the application again through Kestrel, the error should be gone and we can succesfully authenticate through our Windows credentials.

More information: https://docs.microsoft.com/en-us/aspnet/core/security/authentication/windowsauth?view=aspnetcore-6.0&tabs=visual-studio#enable-windows-authentication-with-httpsys

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