501 Not Implemented

HTTP status code 501 Not Implemented. Defined in RFC9110.

http-status kind status-code status standard verification verified tier A iana-registry-row@1

registry record

value: 501

references: RFC9110

source: https://www.iana.org/assignments/http-status-codes/http-status-codes-1.csv
version: IANA registry, Last-Modified: Fri, 24 Oct 2025 07:01:38 GMT
retrieved: 2026-05-29 · updated: 2026-05-29

agent: curl -H 'accept: application/json' wire.phall.io/http-status/501 or /http-status/501.json