HTTP status code 503 — Service Unavailable
Quick answer
Status code 503 (Service Unavailable): Server is temporarily unable to handle the request. Overload, maintenance, or dependency outage — often retryable.
Overload, maintenance, or dependency outage — often retryable.
503 is intentionally temporary. Honor Retry-After when present and avoid hammering during maintenance windows.
Common causes
- Scheduled maintenance mode
- The server is overloaded past its capacity
- A dependency (database, cache) the server needs is down
How to fix it
Honor the Retry-After header if present and back off — hammering a 503 during an outage or maintenance window makes recovery slower.
Frequently asked questions
What is status code 503?
503 Service Unavailable: Server is temporarily unable to handle the request. Overload, maintenance, or dependency outage — often retryable.
When should I expect HTTP 503?
503 is intentionally temporary. Honor Retry-After when present and avoid hammering during maintenance windows.
What usually causes HTTP 503?
Scheduled maintenance mode; The server is overloaded past its capacity; A dependency (database, cache) the server needs is down.
How do I fix HTTP 503?
Honor the Retry-After header if present and back off — hammering a 503 during an outage or maintenance window makes recovery slower.
Where can I see all status codes?
Open the HTTP status codes hub on TryDevSnip for the full reference list.
Does TryDevSnip log my API traffic?
No. These pages are static reference. TryDevSnip does not proxy or inspect your HTTP calls.