What does HTTP status 404 (Not Found) mean?

HTTP_STATUS_NOT_FOUND

A 404 does not tell the client whether the absence is temporary or permanent. When the server knows the resource was intentionally removed and will not return, 410 is more specific.

Check the exact path after redirects, URL encoding, route deployment, host name, and authorization-dependent routing. A cached 404 may also outlive a recent deployment.

RFC 9110: HTTP Semantics

Operational meaning of HTTP 404 for HTTP_STATUS_NOT_FOUND

HTTP 404 (HTTP_STATUS_NOT_FOUND) is a client-error response. AllStat records its meaning as “404 Not Found”. For HTTP_STATUS_NOT_FOUND, interpret it with the request method, selected representation, response headers, and the specification or product that defines the code; the number alone does not prove that application work completed.

Client and server handling for HTTP_STATUS_NOT_FOUND

• Treat HTTP_STATUS_NOT_FOUND as a condition visible at the request boundary; inspect authentication, syntax, preconditions, routing, and resource state before retrying.
• For HTTP_STATUS_NOT_FOUND, preserve the response body and challenge or retry-related headers because they often carry the actionable reason.
• For HTTP_STATUS_NOT_FOUND, automatic retry is safe only when the method and status contract allow it and the request has been corrected.

For telemetry, record HTTP 404, method, authority, route template rather than secrets, response headers relevant to caching or retry, latency, upstream identity, and whether the response originated at the application or an intermediary.

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