HTML Checking for Large Sites

Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.

Attribute “xmlns:og” not allowed here.

The old way for using Open Graph Protocol tags in web pages is not valid HTML5, you should use the updated markup as specified in https://ogp.me

As an example, the following is the Open Graph protocol markup for The Rock on IMDB:

<!DOCTYPE html>
<html lang="en" prefix="og: https://ogp.me/ns#">
<head>
<title>The Rock (1996)</title>
<meta property="og:title" content="The Rock" />
<meta property="og:type" content="video.movie" />
<meta property="og:url" content="https://www.imdb.com/title/tt0117500/" />
<meta property="og:image" content="https://ia.media-imdb.com/images/rock.jpg" />
</head>
</html>

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Related W3C validator issues