503
Service Unavailable
Server errors (5xx)·RFC 9110
What 503 means
The server is temporarily unable to handle the request (overloaded or down for maintenance).
Usually transient. A Retry-After header may indicate when to try again; scale capacity if it persists.
Server errors (5xx)
The server failed to fulfil an apparently valid request.
Other 5xx codes
FAQ — 503
What does HTTP 503 mean?
503 Service Unavailable: The server is temporarily unable to handle the request (overloaded or down for maintenance). Usually transient. A Retry-After header may indicate when to try again; scale capacity if it persists.
Which class does status code 503 belong to?
503 is a Server errors (5xx) code. The server failed to fulfil an apparently valid request.
Where is the 503 code defined?
Status code 503 is defined in RFC 9110 and is part of the IANA HTTP Status Code Registry.