spec checked

MDN HTTP 404 Not Found

Documents 404 as the client error response when the server cannot find the requested resource, distinguishes temporary or permanent ambiguity from 410 Gone, and describes custom 404 pages.

Open source

Pattern Decisions This Source Supports

Pattern Supported decision Required contract Claim note
Page not found page Choose page not found page when the requested route, page, file, object URL, or deep link does not resolve to a valid destination. The page loads as a stable destination instead of redirecting users without explanation. MDN documents 404 as the response when the server cannot find the requested resource and distinguishes it from 410 Gone.

Evidence Role

This source is treated as spec evidence. Use it to validate the decision rules above, not as a visual style reference.

Publisher: MDN Web Docs. Last checked: .