CloudFront: 502 ERROR The request could not be satisfied (origin SSL failure)

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

# Which name does CloudFront use for the origin?
aws cloudfront get-distribution-config --id E123EXAMPLE \
  --query 'DistributionConfig.Origins.Items[].[DomainName,CustomOriginConfig.OriginSslProtocols.Items]'

# Does the origin present a certificate for that exact name?
openssl s_client -connect origin.example.com:443 -servername origin.example.com </dev/null 2>/dev/null \
  | openssl x509 -noout -subject -ext subjectAltName -dates

# Fixes:
#   use a DNS name covered by the certificate as the origin domain
#   serve the full chain, not just the leaf certificate
#   allow TLSv1.2 in the origin's SSL protocols
#   or set Origin Protocol Policy to HTTP only for a private origin

How to diagnose Caching errors

Cache problems are rarely reported as cache problems. They arrive as a traffic spike that takes down the origin (a stampede after a mass eviction), users seeing old content after a deploy, or an inexplicable 403 from the CDN. The unifying diagnostic is to look at the cache status header on a real response before theorising about anything else.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

1. Read the cache status header on a live request: curl -sI https://example.com | grep -i -E 'cache|age|x-cache|cf-cache-status'. HIT, MISS and BYPASS each point at a different root cause.
2. Check the Age header against your intended TTL. An Age larger than max-age means something is serving stale content deliberately (stale-while-revalidate), often the desired behaviour, occasionally the bug.
3. For stampedes, add request coalescing or a short randomised TTL jitter rather than a longer TTL. Identical expiry times across many keys are what create the thundering herd.
4. Use content-hashed filenames for static assets and no-cache for HTML. Almost every "users see the old version" incident traces back to a long TTL on an HTML document.
5. For CDN 403s, distinguish a CDN-generated response from an origin one by checking whether CDN-specific headers are present. An origin 403 has a completely different fix.

Tools worth reaching for

• curl -sI
• varnishlog
• CDN edge logs
• Cache-Control validators

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

📖 docs.aws.amazon.com

Related Caching errors

• Browser serving stale cache after deploymentUsers see old content after a deployment because their browsers cached the previous version…
• Cache stampede / thundering herdMultiple processes simultaneously attempt to rebuild the same expired cache entry…
• CDN: High cache miss ratioThe CDN is not caching responses effectively. Most requests are hitting the origin server…
• Cloudflare: cf-cache-status: DYNAMICDYNAMIC means Cloudflare never considered the response for caching, which is different from a…
• CloudFront: 403 Access DeniedCloudFront cannot access the S3 origin, usually because the bucket policy or Origin Access…
• CloudFront: 504 ERROR The request could not be satisfied (origin timeout)CloudFront reached for your origin and either could not open a connection or got no response…
• Django: CacheKeyWarning: Cache key will cause errors if used with memcachedMemcached keys must be under 250 bytes and contain no spaces or control characters. Django…
• Memcached: SERVER_ERROR object too large for cacheThe item exceeded the maximum item size, one megabyte by default, so it was refused rather…

See all 20 Caching errors →

Browse other categories

• HTTP 494xx client errors, 5xx server errors, redirects, headers and protocol problems.
• JavaScript 42npm resolution, async pitfalls, hydration, memory limits and runtime type…
• Database 41Connections, deadlocks, constraints, replication and memory limits.
• AI 35Rate limits, context windows, GPU memory and model-serving failures.
• Network 35Refused connections, timeouts, resets, MTU problems and port exhaustion.
• Python 35Imports, virtual environments, encoding, concurrency and dependency conflicts.
• Kubernetes 34CrashLoopBackOff, ImagePullBackOff, OOMKilled, RBAC, scheduling and storage.
• Docker 27Daemon connectivity, disk space, image pulls, ports and architecture mismatches.
• System 26Disk space, systemd units, file descriptors, OOM killer and scheduled jobs.
• Cloud 25IAM permissions, quotas, service limits and credential failures.
• Security 25JWT validation, CSRF, OAuth grants, SELinux, SSH host keys and CSP.
• TLS 24Untrusted authorities, expiry, hostname mismatch, chains and cipher negotiation.

Something missing or wrong?

This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.