Service Unavailable
5xx Server Error
Last updated:
The server is currently unable to handle the request due to temporary overloading or maintenance.
Description
SHOULD include a Retry-After header. The classic 'we're down for maintenance' or 'over capacity' response. Search engines treat 503 as temporary and won't drop your URLs from the index.
When to use
Return 503 during maintenance windows, when you're rate limiting at the site level, or when overloaded.
Also searched as
Developers commonly search for 503 using phrases like 503 service unavailable · 503 error · http 503 · 503 service unavailable meaning · service unavailable · 503 status code. All refer to the same HTTP 503 Service Unavailable response.
Specification
RFC 9110 §15.6.4
Examples
HTTP/1.1 503 Service Unavailable
Content-Type: application/json
{"error":"Service Unavailable"}res.status(503).json({ error: "Service Unavailable" });w.WriteHeader(http.StatusServiceUnavailable)
return jsonify({"error": "Service Unavailable"}), 503Debug 503 with these tools
Related status codes
Too Many Requests
The client has sent too many requests in a given amount of time (rate limited).
Bad Gateway
The server, acting as a gateway or proxy, received an invalid response from the upstream server.
Gateway Timeout
The server, acting as a gateway or proxy, did not receive a response from the upstream server in time.