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An attribute could not be parsed from the HTML input, probably due to a typo. Check this guide for a related HTML issue.
Related W3C validator issues
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" />
An invalid attribute has been found on an element. Check the affected tag to ensure attributes are well-formed, and if they are you can consider using custom data attributes.
Quote characters used for attributes can use either single quotes (
') or double quotes (
"), and they must be properly matched, for example:
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>
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