HttpWebRequest Ошибка: базовое соединение было закрыто: непредвиденная ошибка при получении

Question

Я получаю ошибку при получении при попытке сделать запрос POST.

Я понимаю, что это связано с TLS или SSL, но я не могу точно определить, есть ли что-то не так с моим кодом. Почти 99% ответов, которые я уже исследовал, были исправлены при добавлении строки ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;, но эта строка только помогла ошибке не стать из «Неожиданная ошибка при отправке» в «Неожиданная ошибка при получении». Мой код выглядит следующим образом:

Я использую Windows Server 2012 R2.

 public static void Request()
    {
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
        try
        {
            string serverURI = "xxxx";
            string relativeURI = "xxxx";
            Uri serverURL = new Uri(serverURI, UriKind.Absolute);
            Uri relativeURL = new Uri(relativeURI, UriKind.Relative);

            string defaultUsername = "xxxx";
            string defaultPass = "xxxx";

            //Add URL To send request to
            HttpWebRequest oktaLoginRequest = (HttpWebRequest)WebRequest.Create(new Uri(serverURL, relativeURI));
            oktaLoginRequest.ContentType = "application/x-www-form-urlencoded";
            oktaLoginRequest.Accept = "application/json";

            string encoded = Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes(defaultUsername + ":" + defaultPass));
            oktaLoginRequest.Headers.Add("Authorization", "Basic " + encoded);

            string requestBody = "grant_type=password&username=xxxx&password=xxxx!&scope=openid";

            oktaLoginRequest.Method = "POST";
            //Set up our body request

            Stream requestStream = oktaLoginRequest.GetRequestStream();
            byte[] postBytes = Encoding.UTF8.GetBytes(requestBody);
            requestStream.Write(postBytes, 0, postBytes.Length);
            requestStream.Close();

            HttpWebResponse response = (HttpWebResponse)oktaLoginRequest.GetResponse();
            string result;
            using (StreamReader rdr = new StreamReader(response.GetResponseStream()))
            {
                result = rdr.ReadToEnd();
                Console.WriteLine(result);
            }
        }
        catch (Exception exception1)
        {
            Console.WriteLine(exception1.ToString());
        }

        Console.ReadLine();
    }

Я получаю сообщение об ошибке в этой строке: HttpWebResponse response = (HttpWebResponse)oktaLoginRequest.GetResponse();

I также пробовал тот же код, используя объект HttpClient. Я получаю точно такую ​​же ошибку. Код выглядит следующим образом:

    private static readonly HttpClient client = new HttpClient();
    public async static void Request3()
    {
        try
        {
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

            string defaultUsername = "xxxx";
            string defaultPass = "xxxx";

            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.TryAddWithoutValidation("content-type", "application/x-www-form-urlencoded");
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(Encoding.ASCII.GetBytes($"{defaultUsername}:{defaultPass}")));

            client.DefaultRequestHeaders.ExpectContinue = false;

            string url = "xxx.com/oauth2/default/v1/token";
            Uri URL = new Uri(url);

            var values = new Dictionary<string, string>
            {
                { "application/x-www-form-urlencoded", "grant_type=password&username=xxx&password=xxx!&scope=openid" }
            };
            var content = new FormUrlEncodedContent(values);

            var response = await client.PostAsync(URL, content);
            var responseString = await response.Content.ReadAsStringAsync();

            //var responseString = await client.GetStringAsync(URL.AbsoluteUri);

            Console.WriteLine(responseString);
        }
        catch (Exception exception)
        {
            Console.WriteLine(exception.ToString());
        }
        Console.ReadLine();

    }

Полная ошибка:

    System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. ---> System.ComponentModel.Win32Exception: The client
and server cannot communicate, because they do not possess a common algorithm
   at System.Net.SSPIWrapper.AcquireCredentialsHandle(SSPIInterface SecModule, S
tring package, CredentialUse intent, SecureCredential scc)
   at System.Net.Security.SecureChannel.AcquireCredentialsHandle(CredentialUse c
redUsage, SecureCredential& secureCredential)
   at System.Net.Security.SecureChannel.AcquireClientCredentials(Byte[]& thumbPr
int)
   at System.Net.Security.SecureChannel.GenerateToken(Byte[] input, Int32 offset
, Int32 count, Byte[]& output)
   at System.Net.Security.SecureChannel.NextMessage(Byte[] incoming, Int32 offse
t, Int32 count)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, A
syncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byt
e[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyRes
ult)
   at System.Net.TlsStream.CallProcessAuthentication(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionCo
ntext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, C
ontextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, C
ontextCallback callback, Object state)
   at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
   at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.ConnectStream.WriteHeaders(Boolean async)
   --- End of inner exception stack trace ---
   at System.Net.HttpWebRequest.GetResponse()
   at TestOkta.Program.Request() in C:\Users\prvrzaidi\source\repos\TestOkta\Tes
tOkta\Program.cs:line 58

Спасибо.