21 common proxy errors explained with root causes, step-by-step fixes, and code examples. Find your error code below and resolve it in minutes.
You are seeing 403 Forbidden because the target server identified your proxy IP as untrusted.
criticalFix →407: Proxy Authentication RequiredYou are seeing 407 because the proxy gateway rejected your credentials.
criticalFix →429: Too Many RequestsYou are seeing 429 because the target server rate-limited your requests.
warningFix →502: Bad GatewayYou are seeing 502 because an upstream server in the proxy chain returned an invalid response.
criticalFix →503: Service UnavailableYou are seeing 503 because the target server is temporarily unable to handle requests.
criticalFix →504: Gateway TimeoutYou are seeing 504 because the proxy waited too long for the target server to respond.
warningFix →You are seeing Cloudflare 1020 because a Cloudflare firewall rule explicitly blocked your request.
criticalFix →1015: Rate LimitedYou are seeing Cloudflare 1015 because the site Cloudflare rate limiting rule matched your request pattern.
warningFix →1010: BannedYou are seeing Cloudflare 1010 because Cloudflare detected your request as automated and banned the IP.
criticalFix →1009: Browser Integrity Check FailedYou are seeing Cloudflare 1009 because Cloudflare Browser Integrity Check (BIC) detected your request headers as non-browser.
warningFix →You are seeing a reCAPTCHA challenge because the target site uses Google reCAPTCHA to detect automated traffic.
warningFix →hCaptcha: hCaptcha ChallengeYou are seeing an hCaptcha challenge because the target uses hCaptcha for bot detection.
warningFix →Turnstile: Cloudflare Turnstile ChallengeYou are seeing a Cloudflare Turnstile challenge because the site uses Cloudflare managed challenge mode.
warningFix →FunCaptcha: Arkose Labs FunCaptchaYou are seeing a FunCaptcha challenge because the target uses Arkose Labs for bot protection.
warningFix →You are seeing ERR_PROXY_CONNECTION_FAILED because your client cannot establish a TCP connection to the proxy gateway.
criticalFix →DNS_PROBE_FINISHED: DNS Resolution FailedYou are seeing DNS_PROBE_FINISHED_NXDOMAIN because the DNS lookup for the target domain failed through the proxy.
warningFix →TLS_HANDSHAKE: TLS Handshake FailureYou are seeing a TLS handshake failure because the SSL/TLS negotiation between the proxy and the target server failed.
criticalFix →WebRTC: WebRTC IP LeakYou are seeing your real IP exposed through WebRTC because the browser WebRTC API bypasses the proxy.
warningFix →You are seeing a DataDome block because DataDome bot detection identified your traffic as automated.
criticalFix →PerimeterX: PerimeterX / HUMAN BlockYou are seeing a PerimeterX (HUMAN) block because their bot detection flagged your traffic.
criticalFix →Akamai: Akamai Bot Manager BlockYou are seeing an Akamai Bot Manager block because Akamai classified your traffic as automated.
criticalFix →This guide covers 21 proxy and web scraping errors across 5 categories -- HTTP status codes, Cloudflare error codes, CAPTCHA challenges, proxy connection errors, and anti-bot platform blocks. Every entry includes root causes, step-by-step fixes, and working code.
Errors are grouped by category so related issues sit together -- every HTTP status code in one section, every Cloudflare error in another. Each error page also links to related errors for deeper troubleshooting.
Yes. Every error page shows a broken code sample and a fixed version side by side, plus a step-by-step fix sequence you can follow in order.
Contact KnoxProxy support with the exact error message and the request you were making. Most undocumented errors turn out to be variations of the HTTP status codes or anti-bot blocks already covered.
KnoxProxy handles IP rotation, header management, and anti-bot bypass so you never see these errors again. Free trial -- no credit card required.