---
set: 5
code: 503
title: Service Unavailable
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"
---

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 field<sup>[1](#ref-1)</sup> 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.

---

* <span id="ref-1"><sup>1</sup> Retry-After [RFC7231 Section 7.1.3][2]</span>
* Source: [RFC7231 Section 6.6.4][1]

[1]: <http://tools.ietf.org/html/rfc7231#section-6.6.4>
[2]: <http://tools.ietf.org/html/rfc7231#section-7.1.3>