Summary
The server is temporarily unable to handle the request due to overload or maintenance.
When it occurs
Returned during overload, deploys, or maintenance; a Retry-After may indicate when to retry.
Common causes
- Server overloaded or out of workers
- Planned maintenance window
- Autoscaler still spinning up capacity
How to fix
- Scale up capacity or add workers
- Wait and retry per Retry-After
- Check maintenance / deploy status