503
5xx Server ErrorService Unavailable
The server is down for maintenance or overloaded. Try again later.
503 Service Unavailable means the server can't handle the request right now - it's overloaded, restarting, or deliberately down for maintenance. It's meant to be temporary, and a good 503 includes a Retry-After header. Unlike 500, the server is working as designed; it just can't serve you at this moment.
About 5xx Server Error
The server failed to fulfill a valid request. The problem is on the server side, not the client.
How to fix 503 Service Unavailable
- If it's your server, check load, memory, and worker/process limits.
- Confirm it isn't stuck in a deploy or maintenance window.
- Scale up or out if traffic is genuinely exceeding capacity.
- As a client, back off and retry per the Retry-After header.