Not Found

Active

RFC 9110 §15.5.5•Since 1991•Web, APIs, CDNs

HTTP 404 Not Found indicates the server cannot find the requested resource. Defined in RFC 9110 §15.5.5. The most recognizable HTTP error code. Does not indicate whether the absence is temporary or permanent.

Description

The 404 Not Found status code indicates that the origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

A 404 does not indicate whether the condition is temporary or permanent — if the server knows the resource is permanently gone, it should use 410 Gone instead.

The 404 response is cacheable by default unless otherwise indicated by cache controls.

Examples

Request to non-existent resource

http

GET /api/users/99999 HTTP/1.1
Host: api.example.com

404 response

http

HTTP/1.1 404 Not Found
Content-Type: application/json

{"error": "not_found", "message": "User with ID 99999 does not exist"}

Edge Cases

•Some servers return 404 to hide resource existence for security (instead of 403).
•A 404 on an API collection endpoint (GET /users) is unusual — an empty array with 200 is more appropriate.
•Soft-deleted resources: consider 410 Gone if the deletion is permanent and known.
•Search engines treat persistent 404s as a signal to remove the page from the index.

When You'll See This

→URL typed incorrectly
→Resource was deleted without a redirect
→Broken link from another website
→API entity does not exist

Implementation References

Language	Constant
Go	http.StatusNotFound
Rust	http::StatusCode::NOT_FOUND
Python	http.HTTPStatus.NOT_FOUND
Node.js	http.STATUS_CODES[404]
.NET	HttpStatusCode.NotFound
Java	HttpURLConnection.HTTP_NOT_FOUND

History

Present since HTTP/0.9 (1991). The most culturally recognized HTTP status code. Many websites have creative custom 404 pages.

Related Status Codes

410 Gone 403 Forbidden 301 Moved Permanently

FAQ

What does HTTP 404 Not Found mean?

HTTP 404 means the server cannot find the requested resource. The URL may be wrong, the resource may have been deleted, or it may never have existed.

What is the difference between 404 and 410?

404 means 'not found' (might come back). 410 means 'gone' (permanently deleted, won't return). Search engines drop 410 pages from their index faster.

Source: RFC 9110 §15.5.5