HTML Guide
A 504 HTTP status error means the validator was unable to retrieve your HTML document due to a server timeout, not because of any syntactic issue in your HTML.
The W3C Validator retrieves your page over HTTP(S) to check its HTML; a 504 (“Gateway Timeout”) indicates the server did not respond in time. This can be caused by server configuration, network problems, or firewall/restriction policies.
To resolve, check if your website is publicly accessible, loads quickly for external visitors, and isn’t blocking the validator’s requests. If your website requires authentication, is on a private network, or restricts certain IPs, external tools like W3C’s validator won’t be able to access it.
For persistent network errors, consult your web hosting provider or server administrator to resolve connectivity issues.
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