Cloudflare error diagnostic headers

When Cloudflare generates an error page (as opposed to forwarding an error from your origin server), the response includes two diagnostic headers:

cf-error-type: Identifies the error category. Common values:
- 1000 — DNS resolution failure (A record points to a Cloudflare IP)
- 1016 — Origin DNS error (CNAME target does not resolve)
- 1101 — Worker threw an unhandled exception
- 1102 — Worker exceeded resource limits (CPU or memory)
- 52x — Origin connectivity error (521, 522, 523, 524, 525, 526)
cf-error-origin: Identifies which Cloudflare system generated the error.

These headers are present only on Cloudflare-generated error pages, not on errors forwarded from your origin server.

How to capture these headers

Reproduce the error and inspect response headers using one of:

curl -v https://example.com — look for cf-error-type in the response headers
Browser DevTools: select Network > select the failing request > Headers
Export a HAR file and inspect the response headers

`cf-error-type` prefix	Origin	Next step
`1xxx`	DNS / routing layer	Check DNS records; verify no Cloudflare IP in A record
`1101` / `1102`	Workers runtime	Check `wrangler tail` for the exception
`52x`	Origin connectivity	Check origin server is up and reachable