Definition

503 Service Unavailable

A 503 Service Unavailable means the server cannot handle the request right now, often during planned maintenance or overload. Paired with a Retry-After header, it tells crawlers the outage is temporary so pages keep their rankings.

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Related terms

HTTP status code

A three-digit code a server returns to summarize how a request went.

Uptime

The proportion of time a site is reachable and serving requests.

404 error

A status code meaning the requested page could not be found.

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