title: Firebase Invitations Error - Link not working
body: <p>I'm trying to get Firebase invitations working. I've followed the instructions <a href="https://firebase.google.com/docs/invites/android" rel="noreferrer">here</a>.</p>
  
  <p>The code that fires off the invitation process is as follows</p>
  
  <pre><code>        AppInviteInvitation.IntentBuilder intentBuilder = new AppInviteInvitation.IntentBuilder(LanguageManager.getString("title-Invitation"))
                  .setMessage(LanguageManager.formatString("message-INVITATION_{game-name}", ScribbleGame.getGame().getDisplayName()))
                  .setEmailSubject(LanguageManager.formatString("title-TRY_{game_name}", ScribbleGame.getGame().getDisplayName()))
                  .setEmailHtmlContent(emailHtml);
  
          application.startActivityForResult(intentBuilder.build(), ActivityResultConstants.REQUEST_INVITE);
  </code></pre>
  
  <p>The email contains a link inserted using the <code>%%APPINVITE_LINK_PLACEHOLDER%%</code> tag. The invitations are sent as expected.</p>
  
  <p>I've tried both with and without deep links. Without deep links, I get a URL like this, which doesn't work and returns a 404 error.</p>
  
  <p><a href="https://plus.google.com/appinvite/131189621476-3ec41294-23ea-47e7-81d7-9a5fd004de6e" rel="noreferrer">https://plus.google.com/appinvite/131189621476-3ec41294-23ea-47e7-81d7-9a5fd004de6e</a></p>
  
  <p>With deep links, I get a URL like this, which doesn't work and returns a 500 error.</p>
  
  <p><a href="https://sfqj5.app.goo.gl/i/131189621476-b6d8a1cf-81b4-4318-90d0-c32ee1a945e1" rel="noreferrer">https://sfqj5.app.goo.gl/i/131189621476-b6d8a1cf-81b4-4318-90d0-c32ee1a945e1</a></p>
  
  <p>I've done a lot of digging but have failed to establish why the links aren't working.</p>