HttpClient throws WebException instead of HttpRequestException

[divil5000]

Steps to Reproduce

Use the Android HttpClient implementation.

Call HttpClient.SendAsync or probably any of its other methods, on an endpoint that does not exist such as http://localhost:12345.

Expected Behavior

The documentation for HttpClient.SendAsync says it throws HttpRequestException in the event of a problem connecting to a server. It certainly should not throw WebException, which is a legacy exception.

Actual Behavior

WebException is thrown.

Version Information

Microsoft Visual Studio Professional 2019
Version 16.9.1
VisualStudio.16.Release/16.9.1+31105.61
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Version 4.8.04084

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Log File

Not needed.

[grendello]

@divil5000 do you use AndroidHttpClientHandler with System.Net.Http.HttpClient or just the standard System.Net.Http.HttpClient without any replacement handlers?

[divil5000]

In our app we are explicitly passing it:

httpClient = new HttpClient(new Xamarin.Android.Net.AndroidClientHandler());

[grendello]

@divil5000 thanks! I will need to see the entire stack trace or, preferably, it would be great if you could create and attach a simple app that uses exactly the code that fails for you.

[divil5000]

I believe I gave you everything you needed to reproduce this in my initial message. However, I have done the work for you as requested. Here's some code:

        var httpClient = new HttpClient(new Xamarin.Android.Net.AndroidClientHandler());
        try
        {
            var result = await httpClient.GetAsync("https://localhost:12345");
        }
        catch (HttpRequestException)
		{
            // Should get here
		}
        catch (WebException ex)
		{
            // Gets here instead
		}

And here's the stack trace:

{System.Net.WebException: Failed to connect to localhost/127.0.0.1:12345 ---> Java.Net.ConnectException: Failed to connect to localhost/127.0.0.1:12345
at Java.Interop.JniEnvironment+InstanceMethods.CallVoidMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x0006e] in <24e422c426e0468ca1fd74b59870ff08>:0
at Java.Interop.JniPeerMembers+JniInstanceMethods.InvokeAbstractVoidMethod (System.String encodedMember, Java.Interop.IJavaPeerable self, Java.Interop.JniArgumentValue* parameters) [0x00014] in <24e422c426e0468ca1fd74b59870ff08>:0
at Javax.Net.Ssl.HttpsURLConnectionInvoker.Connect () [0x00000] in /Users/builder/azdo/_work/278/s/xamarin-android/src/Mono.Android/obj/Release/monoandroid10/android-29/mcw/Javax.Net.Ssl.HttpsURLConnection.cs:433
at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass44_0.b__0 () [0x0007d] in /Users/builder/azdo/_work/278/s/xamarin-android/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:357
at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:2476
at System.Threading.Tasks.Task.Execute () [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:2319
--- End of stack trace from previous location where exception was thrown ---

at Xamarin.Android.Net.AndroidClientHandler.DoProcessRequest (System.Net.Http.HttpRequestMessage request, Java.Net.URL javaUrl, Java.Net.HttpURLConnection httpConnection, System.Threading.CancellationToken cancellationToken, Xamarin.Android.Net.AndroidClientHandler+RequestRedirectionState redirectState) [0x000e4] in /Users/builder/azdo/_work/278/s/xamarin-android/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:406
--- End of inner exception stack trace ---
at Xamarin.Android.Net.AndroidClientHandler.DoProcessRequest (System.Net.Http.HttpRequestMessage request, Java.Net.URL javaUrl, Java.Net.HttpURLConnection httpConnection, System.Threading.CancellationToken cancellationToken, Xamarin.Android.Net.AndroidClientHandler+RequestRedirectionState redirectState) [0x0016e] in /Users/builder/azdo/_work/278/s/xamarin-android/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:413
at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00286] in /Users/builder/azdo/_work/278/s/xamarin-android/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:287
at System.Net.Http.HttpClient.FinishSendAsyncBuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) [0x0017e] in /Users/builder/jenkins/workspace/archive-mono/2020-02/android/release/external/corefx/src/System.Net.Http/src/System/Net/Http/HttpClient.cs:506
at App2.MainActivity.FabOnClick (System.Object sender, System.EventArgs eventArgs) [0x0003e] in C:\Users\None\source\repos\App2\MainActivity.cs:53 }

[divil5000]

Note: If you attempt to access an internet endpoint with no connection, an Java.Net.UnknownHostException is thrown. The methods on HttpClient should not throw that exception.

[simonrozsival]

@grendello as this recently reappeared in dotnet/runtime#99568. Would it be possible to schedule this for .NET 10?

[grendello]

@simonrozsival definitely fine for .NET 10