问HTTPS调用异常“由于意外的数据包格式，握手失败。”

EN

***Code Snippet:***
 ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
 HttpClient Client = new HttpClient();
 var response = await Client.PostAsync("https://auth.brivo.com/oauth/token", httpContent, cancellationToken).ConfigureAwait(false);

***Exception Thrown:***
System.Net.Http.HttpRequestException occurred
  HResult=-2146233088
  Message=An error occurred while sending the request.
  Source=mscorlib
  StackTrace:
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
       at Sisco.FastPass.AccessControl.Brivo.HttpClientHelper.<PostFormDataRequest>d__5`2.MoveNext()
  InnerException: 
       HResult=-2146233079
       Message=The underlying connection was closed: An unexpected error occurred on a send.
       Source=System
       StackTrace:
            at System.Net.HttpWebRequest.EndGetRequestStream(IAsyncResult asyncResult, TransportContext& context)
            at System.Net.Http.HttpClientHandler.GetRequestStreamCallback(IAsyncResult ar)
       InnerException: 
            HResult=-2146232800
            Message=**The handshake failed due to an unexpected packet format.**
            Source=System
            StackTrace:
                 at System.Net.TlsStream.EndWrite(IAsyncResult asyncResult)
                 at System.Net.PooledStream.EndWrite(IAsyncResult asyncResult)
                 at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)
            InnerException: