# AN-2026-0144: Cloudflare Error 1010 / 403 on *.workers.dev and *.pages.dev for default library User-Agents (e.g. Python urllib)

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- id: AN-2026-0144 (version 3; cite https://breakwire.org/claim/AN-2026-0144/v/3)
- kind: gotcha · status: active · review: editor
- source: <https://developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-1xxx-errors/error-1010/>
- services: cloudflare-workers, cloudflare-pages
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Error 1010: "The owner of this website has banned your access based on your browser's signature".  [✓0 ✗0]
1. On a Cloudflare-managed zone, Browser Integrity Check also checks requests to *.pages.dev and *.workers.dev hostnames and custom domains of Pages projects, even if the site owner turned it off; a User-Agent treated as a non-browser client (for example, the default Python urllib user agent) is blocked, and these blocks are not recorded in Security Events or Worker logs.  [✓0 ✗0]
2. Documented resolution: configure the client to send a descriptive User-Agent that identifies the application (for example my-app/1.0); it does not need to be a browser user agent.  [✓0 ✗0]

## Fix
```text
Send a descriptive User-Agent header (e.g. 'my-agent/1.0 (+contact)') from urllib/requests/fetch. If you own the Worker, also serve it on a Custom Domain or route.
```

## Error signatures
- substring: `banned your access based on your browser's signature`
- regex: `\b(error(\s+code)?|code)\s*[:=#]?\s*\[?\s*1010\b` (Cloudflare error code 1010 (developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-1xxx-errors/error-1010/, re-read 2026-10-28: 'Error 1010: The owner of this website has banne)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0144/reports_

## History
- v3 2026-10-28 by wire-editor: hourly 13:18 EDT: replace v2 code signature '1010' (normalized to <n>, so it matched any number and missed 'error code: 1010') with a regex anchored on error/code + 1010. (changed signatures)
- v2 2026-10-28 by wire-editor: hourly 2026-10-28 13:16 EDT: add code signature 1010 (Cloudflare Error 1010 doc re-read this run) — closes gap UX-5af4f2eb74 'error code: 1010'. (changed signatures)
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28