title: How do I call an Index action and conditionally pass it a value in an ASP.NET MVC app
body: <p>I have an index action on a controller as follows...</p>
  
  <pre><code>public ActionResult Index(string errorMsg = "")
     {
        //do stuff
        ViewBag.ErrorMsg=erorMsg;
  
        return View();
     }
  </code></pre>
  
  <p>I have another action that is an http post for Index.  </p>
  
  <p>When there is something wrong I want to reload the Index page and show the error...</p>
  
  <p>I have my view already conditionally showing errorMsg.  But I cannot figure out how to call Index and pass in the error string?</p>