API Gateway: {"message": "Endpoint request timed out"} (504 after 29 seconds)
The backend (usually Lambda) didn’t respond within API Gateway’s integration timeout (29 seconds by default for REST APIs).
Exact message you may see
Endpoint request timed out{"message": "Endpoint request timed out"}Execution failed due to a timeout error
Seen on:
AWS
Meaning
Even if the Lambda timeout is 15 minutes, the API returns 504 at the integration limit. Long-running work must go async (queue + polling/webhook), or be sped up.
Common causes
- Lambda/backend work takes longer than the integration timeout
- Cold start + slow dependency (DB in VPC, external API)
- Lambda in a VPC without NAT waiting on internet calls
⚡ Quick fix
- Move long tasks to async processing (SQS/Step Functions) and return 202
- Optimise the slow call; add timeouts on outbound requests
- Request a higher integration timeout where supported
Detailed fix by platform
AWS CLI
aws logs tail /aws/lambda/my-fn --since 10m | grep -E 'REPORT|Task timed out'
How to diagnose
- Duration — Lambda REPORT duration
- Dependencies — Slow outbound calls?
- VPC — NAT for internet access?
🔧 Still not fixed?
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Last updated 14 Oct 2026