title: ASP.NET MVC get Exception message in Ajax
body: <p>I have an action : </p>
  
  <pre><code>[HttpPost]
  public ActionResult MyAction(MyModel model)
  {
      ...
      if (model.MyCondition == true)
          throw new Exception("MyMessage);
      ....
  }
  </code></pre>
  
  <p>I'd like get the message "MyMessage" on the Ajax side : </p>
  
  <pre><code>onSuccess: function () {
  ...
  },
  onError: function (jqXHR, textStatus, errorThrown) {
  //I'd like get "MyMessage" here
  }
  </code></pre>
  
  <p>An idea how to do this ? When I check with the debugger I don't see my string.</p>