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.

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

404 Code References

Rails HTTP Status Symbol :not_found

Rust HTTP Status Constant http::StatusCode::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

.NET HTTP Status Constant System.Net.HttpStatusCode.NotFound