CredentialCache.DefaultCredentials and UseDefaultCredentials on .NET8 Core

[yvovonBerg]

Describe the bug
It appears that CredentialCache.DefaultCredentials is being used by RestSharp but it doesn't properly pass through the credentials for some reason. It should connect through Kerberos.

To Reproduce
Does not work on .NET 8 Core:

using System.Net;
using RestSharp;

class Program
{
	static void Main(string[] args)
	{
		var options = new RestClientOptions("https://secure.server.example.com") 
		{ 
			Credentials = CredentialCache.DefaultCredentials
		};

		RestClient Client = new RestClient(options);
		var request = new RestRequest("document/EXAMPLE-1");
		var response = Client.Execute(request);
		Console.WriteLine(response.ErrorMessage);
		Console.WriteLine(response.Content);
	}
}

But does work on .NETFramework v4.8

Expected behavior
It should authenticate correctly.

Stack trace
401 response from the webserver.

Desktop (please complete the following information):

• OS: Windows 10 Enterprise
• .NET version: .NET 8 Core
• Version 111.3.0

Additional context
I've also tried to use the useDefaultCredentials flag and the workaround here: dotnet/runtime#84545 of swapping the credentials and useDefaultCredentials arguments but that does not resolve the issue sadly.

Thank you!

[alexeyzimarev]

Have you tried setting UseDefaultCredentials to true?

[yvovonBerg]

Have you tried setting UseDefaultCredentials to true?

Yes, the same result sadly.

[alexeyzimarev]

RestSharp doesn't really do anything with those credentials apart from configuring the HTTP message handler with these parameters. I would suggest trying to use WinHttpMessageHandler as you are running on Windows. You can use RestClientOptions.ConfigureMessageHandler and configuring it explicitly.

[yvovonBerg]

Thanks, I tried with this as well:

			Client = new RestClient(new RestClientOptions(Url + Api)
			{
				UseDefaultCredentials = true,
				ConfigureMessageHandler = handler =>
				{
					if (handler is HttpClientHandler clientHandler)
					{
						clientHandler.UseDefaultCredentials = true;
					}

					return handler;
				}
			});

Same result :(

[alexeyzimarev]

The code you tried doesn't do more than RestSharp does. I suggested using WinHttpHandler, but I don't know if it will work. If you can make it work with HttpClient, it will work with RestClient.

[ckrueger1979]

Any solution?
We are facing the same issue.

[alexeyzimarev]

Again, RestSharp is not a low-level HTTP client implementation. If there's an issue in the message handler in .NET 8, it will show up in RestSharp too:

• https://stackoverflow.com/questions/79024068/http-call-using-usedefaultcredentials-fails-after-upgrade-to-net-8
• Bug Report: Authentication Validation Error (GenericFailure) in .NET8 dotnet/runtime#105574

Some of the comments suggest that it won't work if the endpoint returns 301 and follow redirects is enabled (default). Some people said it worked fine with .NET 6, some say setting Http version to 1.0 solved their issue where it didn't for others.