HTML Guide

Check the syntax of the affected tag, it’s probably malformed and a < character inside has been interpreted as an attribute.

For example, this code might cause this issue:

<!-- Malformed img tag -->
<img src="photo.jpg" alt="smiling cat" < />

<!-- Fixed img tag -->
<img src="photo.jpg" alt="smiling cat" />

The attribute displayText is not allowed on <span> elements.

This issue is commonly caused by an old integration of ShareThis via Drupal or other CMS - the old code used invalid attributes like displayText, st_url and st_title which were later changed to HTML5 custom data attributes.

The <table> element does not accept a height attribute. Use CSS instead.

The attribute st_title is not allowed on <span> elements.

This issue is commonly caused by an old integration of ShareThis via Drupal or other CMS - the old code used invalid attributes like displayText, st_url and st_title which were later changed to HTML5 custom data attributes.

The attribute st_url is not allowed on <span> elements.

This issue is commonly caused by an old integration of ShareThis via Drupal or other CMS - the old code used invalid attributes like displayText, st_url and st_title which were later changed to HTML5 custom data attributes.

The attribute xmlns:serif is not valid. Check this guide for more information on this issue.

An attribute could not be parsed from the HTML input, probably due to a typo. Check this guide for a related HTML issue.

Quote characters used for attributes can use either single quotes (') or double quotes ("), and they must be properly matched, for example:

<p class="news">...</p>

A common cause for this issue is forgetting to use the equal sign (=), so the HTML parser wrongly believes the quote forms part of the attribute name, for example:

<p class "news">this is wrong</p>