503
Service Unavailable
5xx · Server Error
The server is not ready to handle the request (overloaded or down).
What does HTTP 503 Service Unavailable mean?
The server is temporarily unable to handle the request, usually because it is overloaded or down for maintenance. It is meant to be transient, often with a Retry-After header.
5xx responses indicate the server failed to fulfil a valid request. The problem is on the server side and is not something the client can fix by changing the request.
Common causes
- Server overloaded by traffic
- Planned maintenance
- Failed health checks taking instances out of rotation
How to fix a 503 error
- Scale up capacity or enable autoscaling
- Return a Retry-After header during maintenance
- Investigate what is overloading the server
Related 5xx status codes
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