title: ITunes Connect/Testflight - The request app is not available or does not exist
body: <p>I just moved from distributing beta versions of my iOS app through testflightapp.com to the TestFlight service baked into iTunes Connect. </p>
  
  <p>Some external testers (not tried internal) are having no problem, some are getting this message when they click the invite email link:</p>
  
  <p><img src="https://i.stack.imgur.com/GHofo.png" alt="Testflight app error"></p>
  
  <p>The user has:</p>
  
  <ul>
  <li>Fully updated the iPad. (Version 8.1.2)</li>
  <li>Fully updated Testflight app from the app store. (Version 8.1.2)</li>
  </ul>
  
  <p>The email address I'm inviting is different from the Apple Id but I thought this was not a problem.</p>