title: Exception: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel
body: <p><strong>for firebase notification code</strong></p>
  
  <pre><code>WebRequest tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send"); 
  tRequest.Method = "post";
  tRequest.ContentType = "application/json";
  var data = new{collapse_key = "unassigned", to = deviceToken,data = new
    {body = message,title = title,sound = "default"}
  };
  </code></pre>
  
  <p><strong>message to pass for notifaction on mobile</strong>         </p>
  
  <pre><code>var serializer = new JavaScriptSerializer();
  var json = serializer.Serialize(data);
  Byte[] byteArray = Encoding.UTF8.GetBytes(json);
  tRequest.Headers.Add(string.Format("Authorization: key={0}", applicationId));
  tRequest.Headers.Add(string.Format("Sender: id={0}", senderId));
  tRequest.ContentLength = byteArray.Length;
  </code></pre>
  
  <p><strong>error occur here below code</strong> </p>
  
  <pre><code>using (Stream dataStream = tRequest.GetRequestStream())
  { 
    dataStream.Write(byteArray, 0, byteArray.Length);
   using (WebResponse tResponse = tRequest.GetResponse())
    { 
      using (Stream dataStreamResponse = tResponse.GetResponseStream())
      { 
  
     //code 1
      }     
    }   
  }  
  </code></pre>