ASP.Net Core "System.InvalidOperationException: No authenticationScheme was specified, and there was no DefaultChallengeScheme found."

Update for .NET Core 3.0:

Seems for .NET Core 3.0 the solution is much simpler:

• install the Microsoft.AspNetCore.Authentication.Negotiate NuGet package
• add authentication in ConfigureServices like this:

  services
      .AddAuthentication(NegotiateDefaults.AuthenticationScheme)
      .AddNegotiate();

• use the authentication in Configure (above app.UseAuthorization();)

  app.UseAuthentication();

No need to UseIISIntegration, UseHttpSys or anything.

Original post:

If you get the System.InvalidOperationException "No authenticationScheme was specified, and there was no DefaultChallengeScheme found." it means that ... err... you don't have a default authentication scheme. Solution:

• Install NuGet package Microsoft.AspNetCore.Authentication in your project
• add

  services.AddAuthentication(Microsoft.AspNetCore.Server.IISIntegration.IISDefaults.AuthenticationScheme);

  to the ConfigureServices method.

Update: Note that this is for IIS integration. If you want to use self hosted or Kestrel in debug, you should use HttpSysDefaults.AuthenticationScheme. Funny though, it's the same string value for both constants: "Windows".

Oh, and if you enter the credentials badly when prompted and you can't reenter them, try to restart Chrome (as in this answer)