HttpClient behavior difference between .Net 6 and .Net 5: How to fix?

[raweibel]

Hello everyone,
we are working on an .Net 6 application that is run on a corproate network which requires proxy authentication using the windows credentials. As we were running into problems using HttpClient, we wrote a small test application and noticed that when running in .Net 5 things work as expected, but in .Net 6 they do not.

Our test code:
var handler = new HttpClientHandler();
handler.DefaultProxyCredentials = CredentialCache.DefaultCredentials;
var client = new HttpClient(handler);
var response = await client.GetAsync(requestedURL);
Console.WriteLine($"Response: {response.StatusCode}");

Expected result:
Response: Ok

Result in .Net 5:
Response: Ok

Result in .Net 6:
Unhandled exception. System.ComponentModel.Win32Exception (0x80090308): The token supplied to the function is invalid
at System.Net.NTAuthentication.GetOutgoingBlob(Byte[] incomingBlob, Boolean throwOnError, SecurityStatusPal& statusCode)

Does anyone know if this is a known problem? Is there a way to fix this in .Net 6?

I'm happy to provide more detail if needed.

[huoyaoyuan]

You could open an issue with more details. The exception message looks related to your credentials.