Why is HttpClient failing in Unity?

Question

Before starting, I know I can use the UnityWebRequest class instead. The problem is that it is another library the one that is failing: NEthereum's source code, which makes heavy use of the HttpClient.

So I tried this in a behaviour (2021.3.25):

using System;
using System.Net.Http;
using UnityEngine;

public class SampleBehaviour : MonoBehaviour
{
    public void Start()
    {
        TestHttp();
    }

    private async void TestHttp()
    {
        using var client = new HttpClient();
        client.BaseAddress = new Uri("http://127.0.0.1:8545");
        await client.GetAsync("/").ConfigureAwait(false);
    }
}

(I tried other local addresses, like my LAN ones, considering that http server is attending on 0.0.0.0 and I succeed hitting it with cURL)

BUT when I try this, I get this exception:

SocketException: An address incompatible with the requested protocol was used

Now, the issue is that I use IPv4 in a daily basis in other places. What's wrong? Is it something in the .NET setup in the current Unity version? (I'm using .NET Framework and, again, 2021.3.25)

More context here:

I made this test in Unity:

And still get the error:

While a stand-alone .NET Framework console application does not fail like this:

And, more important: This HttpClient-related things were working before. This happened after moving to a newer version of Unity (the 2021.3.25 I'm using now). This is why I'm posting the question here and not in a pure C#-related site.

Answer 1

You specifically say that you want to use SSL/TLS encryption (SslProtocols = SslProtocols.Tls12,), but the protocol-part of your address is http://, not https://. Try this:

client.BaseAddress = new Uri("https://127.0.0.1:8545");

Also note that you might need a self-signed SSL certificate for the local webserver in order for https to work properly.