Working C# code converted to Powershell results in SocketException - azure

Question

I have the following C# console app which successfully calls an HTTP Post endpoint:
class Program
{
static void Main(string[] args)
{
HttpClient httpClient = new HttpClient();
httpClient.BaseAddress = new Uri("https://DomainOne.azure-api.net");
httpClient.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "8b17badbbfe44e9e933453a8b4d8fc85");
StringContent stringContent = new StringContent("\"hi\"", System.Text.Encoding.UTF8, "application/json");
Task<HttpResponseMessage> task = httpClient.PostAsync("integration/api/Result/CompanyOne", stringContent);
HttpResponseMessage response = task.Result;
var content = response.Content.ReadAsStringAsync().Result;
}
}
This is the equivalent Powershell script I'm trying to use:
$httpClient = New-Object 'System.Net.Http.HttpClient'
$httpClient.BaseAddress = New-Object 'System.Uri'('https://DomainOne.azure-api.net')
$httpClient.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "8b17badbbfe44e9e933453a8b4d8fc85");
$stringContent = New-Object 'System.Net.Http.StringContent'('"hi"', [System.Text.Encoding]::UTF8, 'application/json')
$task = $httpClient.PostAsync('integration/api/Result/CompanyOne', $stringContent)
$response = $task.Result
$content = $response.Content.ReadAsStringAsync().Result
However the $task object contains the following:
System.AggregateException: One or more errors occurred.
---> System.Net.Http.HttpRequestException: An error occurred while sending the request.
---> System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send.
---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)
at System.Net.Sockets.NetworkStream.EndRead(IAsyncResult asyncResult)
--- End of inner exception stack trace ---
at System.Net.TlsStream.EndWrite(IAsyncResult asyncResult)
at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)
--- End of inner exception stack trace ---
at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult, TransportContext& context)
at System.Net.Http.HttpClientHandler.GetRequestStreamCallback(IAsyncResult ar)
--- End of inner exception stack trace ---
The endpoint is hosted in our dev Azure environment behind API Management, and the action method/controller looks like this:
[ApiController]
[Route("api/[controller]")]
public class ResultController : ControllerBase
{
[Route("{providerName}")]
[HttpPost]
public Task<bool> ReceiveMessage(HL7Message message)
{
return Task.FromResult(true);
}
}
Here are the protocol settings in Azure API Management:
Why am I getting the SocketException in Powershell but not in C#, and how can I get it to work in Powershell?

Answer 1

Based on Rick Rainey's helpful comment, you can force the TLS version by adding the line of code below before the HTTP call:
[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]::Tls12
I believe this to be a limitation of the .NET version being used. Any version below .NET 4.6 will default to using a TLS version that is not 1.2.