404 Not Found

This is an educational reference page about HTTP 404 Not Found. The page itself is served as 200 OK so it can be indexed as HTTP documentation.

The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.

What it means

HTTP 404 means the server cannot find a current representation for the requested URL.

Common causes

• The URL is misspelled, deleted, moved, or never existed.
• A route parameter references an object that does not exist.
• The application hides private resources by returning 404 instead of 403.

How to fix it

• Check routing, canonical URLs, redirects, and sitemap entries.
• Return 301 or 308 when content moved permanently.
• Use a helpful 404 page with navigation back to important content.

Example response

HTTP/1.1 404 Not Found
Content-Type: text/html

<h1>Page not found</h1>

Developer notes

404 does not say whether the missing state is temporary or permanent. Use 410 when removal is intentionally permanent.

4xx client error – the request contains bad syntax or cannot be fulfilled