---
description: Reference for the cf-error-type and cf-error-origin response headers present on Cloudflare-generated error pages.
title: Cloudflare error diagnostic headers
image: https://developers.cloudflare.com/og-docs.png
---

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# Cloudflare error diagnostic headers

Last updated Apr 23, 2026|Copy as Markdown| [View as Markdown](https://developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-error-headers/index.md)| [Agent setup](https://developers.cloudflare.com/agent-setup/)

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

## Using cf-error-type for diagnosis

| `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 |

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