title: Intermittent ERR_SSL_PROTOCOL_ERROR error for cross domain request
body: <p>The users of my website are seeing intermittent <code>ERR_SSL_PROTOCOL_ERROR</code> when making cross domain requests to <code>api.flickr.com</code></p>
  
  <p>By intermittent I mean that I've seen this happen 4 times out of ~1200 requests to the api yesterday.</p>
  
  <pre><code>Failed to load resource: net::ERR_SSL_PROTOCOL_ERROR     https://api.flickr.com/services/rest/?method=flickr.photos.getInfo&amp;api_key=.....
  </code></pre>
  
  <p>My site is and AngularJS application running on Google App Engine and is exclusivley avalable on HTTPS.</p>
  
  <p><a href="http://www.sslchecker.com/sslchecker?su=38444fa3f2b83f48a2ce2359778cf6d8">sslchecker shows that my site's certificate &amp; certificate chain</a> is installed correctly. Well, I think it looks ok!</p>
  
  <p><a href="http://www.sslchecker.com/sslchecker?su=fc7aa20af2c44dd990c0e146d4f213c2">sslchecker for <code>api.flickr.com</code></a> shows that <code>ROOT 1</code> of the certificate chain is missing. Is that the problem? Is there any way around that for me?</p>
  
  <p>Any other ideas? Is the problem that our certificates are issues by different authorities maybe?</p>
  
  <p><strong>Edit -</strong> Some other possibly relevant info gleaned from google analytics</p>
  
  <ul>
  <li>Have seen it happen for different OSes - Android, iOS, Windows</li>
  <li>Different browsers - Android, Chrome, Safari</li>
  <li>Different Network Domains</li>
  </ul>