title: What does error mean? : "Forbidden (Referer checking failed - no Referer.):"
body: <p>I have a website running, which appears to be working fine. Yet, now I've seen this error in the logs for the fist time.</p>
  
  <pre><code>Forbidden (Referer checking failed - no Referer.): /pointlocations/
  [pid: 4143|app: 0|req: 148/295] 104.176.70.209 () {48 vars in 1043 bytes} [Wed Jul 26 19:49:35 2017] POST /pointlocations/?participant=A2TYLR23CHRULH&amp;assignmentId=3P4MQ7TPPYF65ANAUBF8A3B38A0BB6 =&gt; generated 2737 bytes in 2 msecs (HTTP/1.1 403) 1 headers in 51 bytes (1 switches on core 0)
  </code></pre>
  
  <p>It happens when posting to <code>/pointlocations/</code>, but only for one specific person ( each <code>participant</code> is unique per account, so I know it's only one person, having this problem repeatedly. Over 500+ other <code>participant</code> have had no such problem/error. </p>
  
  <p>What does this error mean, what is likely causing it and can I fix this?</p>