Ajax HTTP error occured. HTTP Result code: 200
You can't just add arbitrary HTML at the top of a module file - Drupal runs through a process to theme the page, and you need hook into that.

You have a couple of options:


Override html.tpl.php in your theme, and add the tag to the &lt;head&gt; section manually. This is probably the easiest way.
Use drupal_add_html_head() in your module, e.g.

$tag = $element = array(
  '#tag' =&gt; 'meta', 
  '#attributes' =&gt; array(
    'http-equiv' =&gt; 'X-UA-Compatible',
    'content' =&gt; 'IE=edge',
  ),
);
drupal_add_html_head($tag, 'mymodule:ua_compatibility');



Make sure you pick an appropriate hook to do this in (preprocess_page, etc), don't just add it to the top of the file or it won't work.