Why you are being blocked
Every code here says which layer produced it — your proxy, the CDN, the anti-bot vendor or the site itself — because that is the fact that decides what to do next. Guessing wrong costs an afternoon.
17 of these 38 are not proxy problems. A 525 is the site's own TLS to its origin; a 1010 is your browser signature; a 407 is your credentials. Each page says so plainly rather than selling you IPs that would not have helped.
HTTP status codes
407
Proxy Authentication Required
403
Forbidden
429
Too Many Requests
401
Unauthorized
502
Bad Gateway
503
Service Unavailable
504
Gateway Timeout
400
Bad Request
408
Request Timeout
451
Unavailable For Legal Reasons
405
Method Not Allowed
413
Payload Too Large
421
Misdirected Request
426
Upgrade Required
ip_not_allowed
ip_not_allowed — your IP is not on the allowlist
Cloudflare errors
1015
Cloudflare error 1015 — You are being rate limited
1020
Cloudflare error 1020 — Access denied
1006
Cloudflare error 1006 — Access denied, your IP has been banned
1009
Cloudflare error 1009 — Access denied, country blocked
1010
Cloudflare error 1010 — Browser signature banned
520
Cloudflare error 520 — Web server returned an unknown error
521
Cloudflare error 521 — Web server is down
522
Cloudflare error 522 — Connection timed out
524
Cloudflare error 524 — A timeout occurred
1101
Cloudflare error 1101 — Worker threw exception
Anti-bot blocks
DataDome
DataDome block page
PerimeterX
PerimeterX / HUMAN block
Akamai
Akamai "Access Denied" with a reference number
CAPTCHA loop
Endless CAPTCHA — solving it changes nothing
Connection errors
ENOTFOUND
ENOTFOUND — DNS lookup failed
ERR_EMPTY_RESPONSE
ERR_EMPTY_RESPONSE / empty reply from server
ERR_TUNNEL_CONNECTION_FAILED
ERR_TUNNEL_CONNECTION_FAILED
ERR_PROXY_CONNECTION_FAILED
ERR_PROXY_CONNECTION_FAILED
ECONNRESET
ECONNRESET — connection reset by peer
ETIMEDOUT
ETIMEDOUT — connection timed out
TLS & certificates
CERTIFICATE_VERIFY_FAILED
Certificate verify failed / expired
525
Cloudflare error 525 — SSL handshake failed
SSL handshake failed
TLS handshake failure through a proxy
When it is the IP
Residential IPs across 199 countries, from $7.35/GB — no commitment.
Get residential IPs →