Using HttpClient in new WebApi project

Question

I have created a new Webapi2 project and I am trying to call an external web service using this code:

WebServiceAuthResult authResult = new WebServiceAuthResult();
using (var httpClient = new HttpClient())
{
    httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", credentials);
    try
    {
        var response = await httpClient.PostAsync(url, null);

        var responseContent = await response.Content.ReadAsStringAsync();
        authResult = JsonConvert.DeserializeObject<WebServiceAuthResult>(responseContent);
    }
    catch (Exception ex)
    {
    }
}

I am getting this error:

Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

I have used the exact same code in a UWP project and it works perfectly - So I am guessing there's something wrong in my project set up.

I've looked at Google and other StackOverflow questions about this but they all suggest an issue with the web service - but I know this is working as I can test using my UWP project.

Can anyone suggest anything for me to try?

If code works locally, but doesn't work at deployed server, then it can be related to policy of deployed server. — Yuriy Zaletskyy, Jul 11 '16 at 10:02
How is your service deployed? If it's self hosted the problem might be the account the service uses: https://msdn.microsoft.com/en-us/library/system.serviceprocess.serviceaccount(v=vs.110).aspx — lavuy, Jul 11 '16 at 10:09
I'm just testing locally at the moment. my UWP app is running locally also using a windows phone emulator. I have no information about how the web service I am calling is set up — Percy, Jul 11 '16 at 10:11
Have you enabled basic authentication on your web server? If you're using IISExpress to test do the instructions mentioned [here](http://stackoverflow.com/questions/25642787/basic-authentication-on-iis-express). If you're using say IIS 7, use [this one](https://technet.microsoft.com/en-au/library/cc772009(v=ws.10).aspx). — akardon, Jul 11 '16 at 13:46

score 2 · Accepted Answer · answered Jul 11 '16 at 13:53

As is usually the case with these questions the answer is a one liner but has taken 4 hours to resolve!

By adding this line of code the connection to the web service is successful:

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;

I've added the code in the using statement but I think it's only required once so if anyone can tell me where is the best place to add this code and why I need it in my WebApi project and not my UWP project?

Using HttpClient in new WebApi project

1 Answers1