HTML Validation
HTML Guides for rate limit
Learn how to identify and fix common HTML validation errors flagged by the W3C Validator — so your pages are standards-compliant and render correctly across every browser. Also check our Accessibility Guides.
The “HTTP resource not retrievable” error with an HTTP status code of 429 indicates that the W3C Validator was temporarily blocked from accessing a specific URL because the remote server is rate-limiting incoming requests. This typically happens when too many requests are made in a short period of time.
To resolve this:
- Try checking the site at a lower speed, or less often.
- If you’re the server owner, check your server or CDN settings for rate-limiting rules that might be too aggressive.
This error is usually temporary. Waiting before retrying can often resolve the issue.
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