I'm trying to validate my Drupal 7 website on http://validator.w3.org but I can't keep getting the following error:

Attribute datatype not allowed on element meta at this point.

This is because <meta about="/frontpage" property="sioc:num_replies" content="0" datatype="xsd:integer" /> automatically gets the 'datatype=xsd:integer' attribute. I want to remove the datatype attribute altogether.

3 Answers 3


Apparently the meta tag isn't the problem. The problem is the validation service and how you use it. After some digging I found this article. The author suggest using a different validation type namely: http://validator.w3.org/nu/ with the following preset set in the additional options: "HTML5 + SVG 1.1 + MathML 2.0 + RDFa 1.1 + Microdata". This will validate said meta tags without any errors.

  • The presets have changed; use "HTML5 + SVG 1.1 + MathML 3.0 + RDFa 1.1 + Microdata"
    – mrP
    Commented May 22, 2013 at 2:04

I don't know what effect this will have on the validity of that particular tag, but you can remove the property by implementing hook_html_head_alter() (either in your theme or a custom module file):

function MYTHEME_html_head_alter(&$head_elements) {
  if (isset($head_elements['rdf_node_comment_count'])) {

Use this function to alter meta tags...

// hook_html_head_alter().
function YOUR_THEME_html_head_alter(&$head_elements) {
  dsm($head_elements); // if you have Devel installed
  var_dump($head_elements); // else use standard PHP dump

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