WebException in Xamarin, using HttpClient

Question

I'm learning how to use xamarin with C#, and I've got an android app to make web requests to an external API and I'm receiving the following error;

System.Net.Http.HttpRequestException: An error occurred while sending the 
request ---> System.Net.WebException: Error: SecureChannelFailure (The   
authentication or decryption has failed.) ---> System.IO.IOException: The 
authentication or decryption has failed. ---> System.IO.IOException: The 
authentication or decryption has failed. ---> 
Mono.Security.Protocol.Tls.TlsException: The authentication or decryption has failed.

My code is as following;

public async Task<List<T>> GetList<T>(string url)
    {
        HttpClient client = new HttpClient();
        var response = await client.GetAsync(new Uri(url));
        response.EnsureSuccessStatusCode();
        var content = await response.Content.ReadAsStringAsync();
        return JsonConvert.DeserializeObject<List<T>>(content);
    }

The MainClass in android calls the core class, which calls this service class.

HttpClient requests work when the API does not use HTTPS, but throws this error whenever I use an API that has HTTPS enabled.

I'm also using a Portable Class Library to store code, so using HttpWebRequest for web requests isn't possible.

I have also tried;

ServicePointManager.ServerCertificateValidationCallback += (o, certificate, chain, errors) => true;

And;

System.Security.Cryptography.AesCryptoServiceProvider b = new System.Security.Cryptography.AesCryptoServiceProvider();

In my application OnCreate class (android).

I have also changed the HttpClient implementation to AndroidClientHandler, along with changing the SSL/TLS implementation to 1.1. Along with attempting this on an emulator and a device.

Does anyone have any advice?

Were you able to resolve this? I ran into the same issue and modifying the Android project worked for me. Under Android Options > Advanced, I set HttpClient implementation to Android and SSL/TLS implementation to Native TLS 1.2+ — nthpixel
– nthpixel, Commented Aug 6, 2017 at 20:54
I was also getting the same above error @Yanbin Hu good solution and apart from changing the HTTP client implementation from Default to Android native also changed SSL/TLS implementation from Default to - Native TLS 1.2+ - then it worked for me. — SK Ashok
– SK Ashok, Commented Dec 15, 2017 at 8:51

Yanbin Hu · Accepted Answer · 2017-10-05 12:12:36Z

12

Try this: Open Android project property -> Android Options -> Advanced

Switch the HttpClient implementation setting from Default to Android

It seems that the default Mono client handler is broken for HTTPS.

answered Oct 5, 2017 at 12:12

Yanbin Hu

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3 Comments

Josh Mc Over a year ago

Will mention that leaving HttpClient Implementation as default, and updating TLS to be 1.2+ worked for me

Kishor Bikram Oli Over a year ago

Best solution. I don't know why these things need to be done. Is this standard one or just a hack?

Mohan Perera Over a year ago

Worked for me. I changed HttpClient implementation to Android. SSL/TLS implementation to Default.

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