---
set: 5
code: 503
title: Service Unavailable
references:
    "Rails HTTP Status Symbol": ":service_unavailable"
---

The 503 (Service Unavailable) status code indicates that 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 ([RFC7231 Section 7.1.3][2]) 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.

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>