title: Outlook Add-In's stoped working, because outlook web interface want to confirm domain using dialog which is blocked by browser
body: <p>Somewhere between 13.Oct and today (16. Oct) I (and no one else in our company) can no longer use Outlook Add-Ins in Outlook. This is true for Add-Ins added by the user and Add-Ins deployed by the administrator. (We do not have Add-Ins installed from the Store)</p>
  <p>The website started asking if the domain is trusted with a confirmation dialog. However this seems to be prevented by the browser (chrome and Firefox) I assume because the <code>allow-modals</code> is not set on the frame that hosts the Add-In. I tested to manipulate the website using fiddler to include the <code>allow-modals</code> and the dialog appeared and after confirmation the add-in worked.</p>
  <p><a href="https://i.stack.imgur.com/nsGXg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nsGXg.png" alt="Confirmation Dialog" /></a></p>
  <p>Our Admin says he did not update the Exchange server in the past days. Since It happens in multiple browsers now, I also suspect it was not an silent update of the browser.</p>
  <p>We are using the &quot;old&quot; OWA UI. And the Add-Ins open a task panel to the side. This displays an error:</p>
  <p><a href="https://i.stack.imgur.com/boLSA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/boLSA.png" alt="Error in Panel" /></a></p>
  <p>The English version has following Text:</p>
  <blockquote>
  <p>This add-in has been disabled to help keep you safe. To continue using the add
  in, validate that this item is hosted in a trusted domain or open it in the
  Office desktop app.</p>
  </blockquote>
  <p>Using the continue button does nothing. (It shows a text that nothing can be done, without providing any information)</p>
  <p>Does anyone have an Idea what could have changed? And how to turn it back or mitigate it?<br />
  Some Add-In are deployed by the Admin, so the User should not need to confirm the domain is trusted.</p>