Diagnosing Cloudflare Blocks Before Changing Your Scraper

A scraper fails, someone swaps the User-Agent, someone else adds a proxy, then the job starts passing locally but fails again in CI. That usually happens because Cloudflare did not block “scraping” as one thing. It evaluated several signals, and each failure needs a different fix. This is about authorized automation: your own sites, customer-approved workflows, testing, monitoring, data access you are allowed to perform. If you do not have permission to automate against a site, changing fingerprints or rotating IPs does not make it okay. Start with the failure you actually see Cloudflare failures often get collapsed into “403”, but the page body matters. Common cases: Error 1020 : usually an access denied page from a Cloudflare rule or bot score decision. The HTTP status may still be 403, so inspect the HTML. 403 without a 1020 page : often IP reputation, firewall rules, geo restrictions, or an auth problem. 429 : rate limit exhaustion. Slowing down can help here, but it will not fix a fingerprint problem. Endless Just a moment... page : your client did not complete the browser-side challenge. CAPTCHA or Turnstile loop : Cloudflare still considers the session borderline after earlier checks. Add classification before you add workarounds. Even a basic classifier saves time: import time import requests CLOUDFLARE_MARKERS = { " 1020 " : " cloudflare_access_denied " , " Just a moment " : " cloudflare_js_challenge " , " cf-turnstile " : " cloudflare_turnstile " , " cf-error-code " : " cloudflare_error_page " , } def classify_response ( resp : requests . Response ) -> str : body = resp . text [: 5000 ] if resp . status_code == 429 : return " rate_limited " for marker , label in CLOUDFLARE_MARKERS . items (): if marker in body : return label if resp . status_code == 403 : return " forbidden_unknown " return " ok " if resp . ok else f " http_ { resp . status_code } " def get_with_backoff ( url : str , max_attempts = 4 ): for attempt in range ( max_attempts ): resp = request