title: The remote server returned an error: (422) Unprocessable Entity
body: <p>I am trying to send post request, But I am facing issue with 'The remote server returned an error: (422) Unprocessable Entity.' , I had try lot, but no success, 
  Anyone can please tel me , what is wrong with my bellow code.</p>
  
  <pre><code>HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://url.com");
  request.Method = "POST";
  request.KeepAlive = false;
  request.Accept = "application/json";
  request.Headers.Add("Authorization", "Bearer e*******");
  
  using (var streamWriter = new StreamWriter(request.GetRequestStream()))
  {
      string json = new JavaScriptSerializer().Serialize(new
      {
          mobile_number = "9763641790",
          first_name = "suraj",
          last_name="mahajan"
      });
      streamWriter.Write(json);
      streamWriter.Flush();
      streamWriter.Close();
  }
  
  var response = (HttpWebResponse)request.GetResponse();
  var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
  </code></pre>