What does a CDN error decoder do?
It matches an HTTP status and response headers to known provider signatures, then returns a concise explanation when a provider-specific diagnostic is available.
Free CDN diagnostic
CDN error decoder
Decode Cloudflare, Vercel, and AWS CDN errors. Enter an HTTP status and response headers to get a concise explanation and practical troubleshooting steps.
Decode a CDN or gateway error
Paste a captured HTTP response or enter a status and headers. Only the status and response headers are sent; common credential headers are filtered first.
Find the cause of the next outage sooner
During an outage, every second counts. SteadyNode's uptime engine translates CDN errors into likely root causes on every check.
No credit card required.
Start for freeCommon CDN and gateway errors
Choose a provider-specific guide to troubleshoot edge, gateway, and function failures.
Cloudflare
- HTTP 520Cloudflare Error 520: Unknown Origin Error
- HTTP 521Cloudflare Error 521: Web Server Is Down
- HTTP 522Cloudflare Error 522: Connection Timed Out
- HTTP 523Cloudflare Error 523: Origin Is Unreachable
- HTTP 524Cloudflare Error 524: Origin Response Timeout
- HTTP 525Cloudflare Error 525: SSL Handshake Failed
- HTTP 526Cloudflare Error 526: Invalid SSL Certificate
- HTTP 530Cloudflare Error 530: Origin DNS Error
Vercel and Netlify
AWS CloudFront and ALB
- HTTP 502CloudFront 502: Origin TLS or Response Mismatch
- HTTP 504CloudFront 504: Origin Gateway Timeout
- HTTP 503CloudFront 503: Origin Service Unavailable
- HTTP 403CloudFront 403: Origin Access Denied
- HTTP 503AWS ALB 503: Target Group Has No Healthy Targets
- HTTP 502AWS ALB 502: Target Reset or Invalid Response
- HTTP 504AWS ALB 504: Target Response Timed Out
Fastly
Heroku and Render
Nginx and Envoy
Frequently asked questions
Are response headers sent in the URL?
No. Header values are submitted in the HTTPS request body and are not written to usage telemetry.