title: Sharepoint 2013 Apps - Inconsistent error behavior with AppRedirect.aspx
body: <p>As described in the title, the app simply stops working after some time.</p>
  
  <p>The application itself is a simple, one page form that pulls data from a webapi on another webserver by use of the Sharepoint WebProxy and displays that data using knockout.js. The environment and the Sharepoint Server (On-Premise, same domain as my Dev Machine) are configured correctly - supposedly - as described in</p>
  
  <p><a href="http://technet.microsoft.com/en-us/library/fp161236.aspx" rel="nofollow">Configure an environment for apps for SharePoint (SharePoint 2013)</a></p>
  
  <p>I can develop, debug in VS, deploy and open the App directly on the Sharepoint Site. </p>
  
  <p>But after a while, when opening the app again without having changed or redeployed anything it stops at this point in the redirect process:</p>
  
  <pre><code>https://sharepointurl/_layouts/15/appredirect.aspx?instance_id=&lt;some-guid&gt;
  </code></pre>
  
  <p>and shows the "This page cannot be displayed" message. The Sharepoint Site still works. </p>
  
  <p>There are no errors in the eventlog. Most of the time I can fix this by restarting the IIS service completely on which the Sharepoint Site resides. But sometimes even that doesnt work.</p>
  
  <p>What could be the problem? Any Idea?</p>
  
  <p><strong>Update:</strong> The error is not consistent in that it may occur for user A but not for user B and even that can exchange after some time, so that the user B sees the error and user A can use the App.</p>
  
  <p><strong>Update:</strong> The error only occurs in IE 11 and doesn't happen when using Google Chrome.</p>
  
  <p><strike><strong>Update:</strong> It seems as if Sharepoint 2013 Apps <strong>do not work with Internet Explorer 11</strong>, which I was using. As we had other issues with IE 11 and Reporting I downgraded my development machine to IE 10 and now it works.</strike></p>
  
  <p><strong>Update:</strong> This had nothing to do with IE 11 either. The error eventually returned.</p>