title: What causes XML Parsing Error: no root element found error?
body: <p>I recently started getting the following error displayed in Firebug:</p>
  
  <blockquote>
    <p>XML Parsing Error: no root element found Location: <a href="http://dd.example.com/1.0/sources/30" rel="nofollow noreferrer">http://dd.example.com/1.0/sources/30</a> Line Number 1, Column 1:  30:1:1</p>
  </blockquote>
  
  <p>What causes it and how do I fix it?</p>
  
  <p>Headers tab:</p>
  
  <pre><code>Request URL: http://dd.example.com/1.0/sources/30
  Request Method: PUT
  Remote address: 11.11.111.111:80
  Status Code: 204 No Content
  Version: HTTP/1.1
  </code></pre>
  
  <p>Request Headers:</p>
  
  <pre><code>Host: dd.example.com
  User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0
  Accept: */*
  Accept-Language: en-US,en;q=0.5
  Accept-Encoding: gzip, deflate
  Referer: http://dd.example.com/
  Content-Type: application/x-www-form-urlencoded; charset=UTF-8
  X-Requested-With: XMLHttpRequest
  Content-Length: 33
  Cookie: _ga=GA1.2.1885184115.1475238275; PHPSESSID=7ggri150scu2g5et1f7gtone94
  Authorization: Basic TEljaGGlcDqTdW5zaKfrZX==
  Connection: keep-alive
  </code></pre>
  
  <p>Request Body:</p>
  
  <pre><code>name=name&amp;value=Remote+Sock&amp;pk=30
  </code></pre>
  
  <p>Response Headers:</p>
  
  <pre><code>Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
  Connection: close
  Content-Length: 0
  Content-Type: 
  Date: Sun, 05 Feb 2017 16:59:50 GMT
  Expires: Thu, 19 Nov 1981 08:52:00 GMT
  Pragma: no-cache
  Server: Apache/2.2.15 (CentOS)
  X-Powered-By: PHP/5.
  </code></pre>