4×× - Client Error

404 Not Found

The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

A 404 status code does not indicate whether this lack of representation is temporary or permanent; the 410 Gone status code is preferred over 404 if the origin server knows, presumably through some configurable means, that the condition is likely to be permanent.

A 404 response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls¹.

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• ¹ Calculating Heuristic Freshness RFC7234 Section 4.2.2
• Source: RFC7231 6.5.4

404 Code References

• Rails HTTP Status Symbol: :not_found
• Go HTTP Status Constant: http.StatusNotFound
• Symfony HTTP Status Constant: Response::HTTP_NOT_FOUND
• Python2 HTTP Status Constant: httplib.NOT_FOUND
• Python3+ HTTP Status Constant: http.client.NOT_FOUND
• Python3.5+ HTTP Status Constant: http.HTTPStatus.NOT_FOUND