How to fix: Element "g:plusone" undefined

Most Likely Cause and Fix

Your markup contains a non-standard <g:plusone> element for rendering a +1 button for Google's social network.

The documentation has alternative markup that is valid HTML5:

<div class="g-plusone" data-size="tall" ... ></div>

What This Error Means

This error is stating that your markup contains a <g:plusone> element (or <>) and that such an element is not defined.

HTML consists of a predefined set of elements. You can't validly use an element that does not exist.

How To Fix It

For uppercase element names

You have a XHTML document which recognises only lowercase element names as being valid and have in your markup a element in uppercase.



instead of:


In general

If you've not inadvertently used an uppercase element in place of the correct lowercase element, you have very likely used an element that does not exist in the version of HTML you are using.

Check the document type declaration used in your markup. Fix this if not correct.

If you're still running into 'element "g:plusone" undefined' errors, you're simply using an invalid, undefined element. Don't.

Discuss, Comment and Improve

Did this help you? Can this page be improved? Let us know!

comments powered by Disqus