tool::http-status-detail
503 Service Unavailable
The server is temporarily unable to handle the request.
Status Code
503
Name
Service Unavailable
Category
5xxDetailed Explanation
HTTP 503 Service Unavailable indicates that the server is temporarily unable to handle requests. This is caused by overload, maintenance, or intentional downtime. Unlike 502, the server itself is functional but is currently unable to provide service. The Retry-After header can inform clients when to retry.
Common Causes
- ▸Server maintenance or planned downtime
- ▸Server overload due to a traffic spike
- ▸Requests rejected due to rate limiting
- ▸Backend dependencies (database, external API) are unresponsive
- ▸Server restart during deployment
How to Fix
- 1.If a Retry-After header is present, retry after the specified time
- 2.Check server resources and scale up/out if needed
- 3.Use a load balancer to distribute traffic
- 4.If under maintenance, inform users of the expected recovery time
- 5.Set up auto-scaling to automatically handle traffic spikes
Related HTTP Headers
Retry-AfterCache-ControlResponse Example
HTTP/1.1 503 Service Unavailable
Retry-After: 300
Content-Type: application/json
{"error":"service_unavailable","message":"Server is under maintenance. Please retry after 5 minutes."}Related Status Codes
500Internal Server ErrorThe server encountered an unexpected condition.→501Not ImplementedThe server does not support the requested functionality.→502Bad GatewayThe gateway received an invalid response from an upstream server.→504Gateway TimeoutThe gateway did not receive a timely response from an upstream server.→505HTTP Version Not SupportedThe HTTP version used in the request is not supported.→
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