5×× SERVER ERROR

503 SERVICE UNAVAILABLE

The server is currently unable to handle the request due to a temporary overload or scheduled maintenance, which will likely be alleviated after some delay.

The server MAY send a Retry-After header field¹ to suggest an appropriate amount of time for the client to wait before retrying the request.

Note: The existence of the 503 status code does not imply that a server has to use it when becoming overloaded. Some servers might simply refuse the connection.

Retry-After RFC7231 Section 7.1.3

503 SERVICE UNAVAILABLE Source: RFC7231 Section 6.6.4

 

503 CODE REFERENCES

Rails HTTP Status Symbol :service_unavailable

Go HTTP Status Constant http.StatusServiceUnavailable

Symfony HTTP Status Constant Response::HTTP_SERVICE_UNAVAILABLE

Python2 HTTP Status Constant httplib.SERVICE_UNAVAILABLE

Python3+ HTTP Status Constant http.client.SERVICE_UNAVAILABLE

Python3.5+ HTTP Status Constant http.HTTPStatus.SERVICE_UNAVAILABLE

 

Recommended:

• 502 BAD GATEWAY
• 501 NOT IMPLEMENTED