title: XSLTProcessor::transformToXml() ID * already defined
body: <p>I'll preface this by saying I'm not server admin, but a developer trying to figure out what went wrong.</p>
  
  <p>Our server, which hosts quite a few websites, was upgraded today by the company which manages it  (while performing other work). The upgrade ended up breaking a lot of our sites (around 30+) which are now throwing XSLT errors.</p>
  
  <p>Most of the sites are built on symphony CMS (not symfony) which uses XSLT templating to generate the (X)HTML. </p>
  
  <p>Before the update we managed to output multiple IDs on the same page with the same value (eg, id='abc', I know, not valid - ignore that for now). The point was it was working without causing errors.</p>
  
  <p>After the upgrade the sites are all throwing errors now when multiple id values are encountered. eg:</p>
  
  <pre><code>ID abc already defined
  </code></pre>
  
  <p>One of the updates, which I'm convinced is causing the error, was to the libxslt, libxml and libexslt version. Before we were using:</p>
  
  <pre><code>libxslt Version =&gt; 1.1.26 
  libxslt compiled against libxml Version =&gt; 2.7.8 
  libexslt Version =&gt; 1.1.26
  </code></pre>
  
  <p>Since the upgrade:</p>
  
  <pre><code>libxslt Version =&gt; 1.1.28  
  libxslt compiled against libxml Version =&gt; 2.9.1   
  libexslt Version =&gt; 1.1.28  
  </code></pre>
  
  <p>My hunch is that it's now treating the XHTML as XML as opposed to HTML, which it did previously, and the XMl doesn't allow multiple ID values.</p>
  
  <p>My question is, has anyone seen this before or know what might be causing it, and what's the appropriate steps to either revert it or force it to ignore multiple id values?</p>
  
  <p>There is no real option at this stage to roll back the changes (so the server admin people say) or to fix the websites (as it would take too long). </p>
  
  <p>Any ideas appreciated.</p>
  
  <hr>
  
  <p><strong>EDIT NOV 24 2014:</strong> Looks like it's an issue in libxml v2.9.1, and not a libxslt issue like I originally thought. I presume downgrading the version of libxml to &lt; v2.9.1 and recompile will work if you have that option to available to you.</p>
  
  <p>I have also logged a bug report to xml[at]gnome.org </p>