I got this exception that doesn't appear anywhere on Google while I was debugging a .NET Core web app. You just have to enable Windows Authentication in the project properties (Debug tab). Duh!

System.InvalidOperationException: The Negotiate Authentication handler cannot be used on a server that directly supports Windows Authentication. Enable Windows Authentication for the server and the Negotiate Authentication handler will defer to it.
   at Microsoft.AspNetCore.Authentication.Negotiate.PostConfigureNegotiateOptions.PostConfigure(String name, NegotiateOptions options)
   at Microsoft.Extensions.Options.OptionsFactory`1.Create(String name)
   at Microsoft.Extensions.Options.OptionsMonitor`1.<>c__DisplayClass11_0.<Get>b__0()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Options.OptionsCache`1.GetOrAdd(String name, Func`1 createOptions)
   at Microsoft.Extensions.Options.OptionsMonitor`1.Get(String name)
   at Microsoft.AspNetCore.Authentication.AuthenticationHandler`1.InitializeAsync(AuthenticationScheme scheme, HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationHandlerProvider.GetHandlerAsync(HttpContext context, String authenticationScheme)
   at Microsoft.AspNetCore.Authentication.AuthenticationService.ChallengeAsync(HttpContext context, String scheme, AuthenticationProperties properties)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

This translates to a change in Properties/launchSettings.json like this:

{
  "iisSettings": {
    "windowsAuthentication": true,
    "anonymousAuthentication": true,
    //...
  },
  //...
}

Comments

Scotty Mac Dev

That&#39;s the question I have! How do I make it run as a self-hosted exe?

Scotty Mac Dev

Siderite

This article on Microsoft&#39;s site should help out: https://docs.microsoft.com/en-us/aspnet/core/security/authentication/windowsauth Check out the last section.

Siderite

Christopher P Painter

Thanks, this makes it work in Visual Studio debugger using IIS. But let&#39;s say you plan on self hosting this as an EXE and not running it through IIS. Any ideas on how to fix that?

Christopher P Painter

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