HTTP Errors Glossary

HTTP 429 Too Many Requests is the status code a server returns when a client has sent more requests in a given window than the server's rate limit allows.

HTTP 499 Client Closed Request is a non-standard status code, logged by Nginx (and CDNs like Cloudflare) when the client closes the connection before the server finishes sending a .

HTTP 403 Forbidden means the server understood your request but refuses to answer it.

HTTP 503 Service Unavailable means the server can't handle your request right now — usually because it's overloaded, under maintenance, or deliberately turning traffic away at its .

HTTP 200 OK is the standard "success" status code: the server got your request, handled it, and sent back the response you expected.

Cloudflare error 1015 "You are being rate limited" means a website is blocking you because you sent too many requests too quickly.

HTTP 402 Payment Required is the status code a server sends to say: "I won't do this until a payment, billing, or quota problem is fixed." It was set aside in the original HTTP spe.

HTTP 404 Not Found is the server's way of saying "I understood your request, but there is nothing at this address." The server is working fine - it just has no page, file, or data .

HTTP 520 is a non-standard Cloudflare status code meaning the origin server returned a response Cloudflare cannot interpret.

HTTP 401 Unauthorized means the server doesn't know who you are because your request didn't include valid login credentials.

HTTP 405 Method Not Allowed means the page exists, but it won't accept the HTTP method (the verb, like GET or POST) you used to ask for it.

HTTP 406 Not Acceptable means the server can't return content matching your Accept headers.

HTTP 409 Conflict means your request clashes with the resource's current state, so the server refuses it.

HTTP 422 Unprocessable Entity means the server understood your request perfectly but refused to act on it because the data inside failed a validation check.

HTTP 451 "Unavailable For Legal Reasons" means a server is refusing to give you a page because the law — not a technical problem — says it cannot.

HTTP 502 Bad Gateway means one server, acting as a middleman, got a broken reply from another server behind it.

HTTP 521 Web Server Is Down is the error Cloudflare shows when it cannot reach the website's actual server.

Cloudflare Error 1020 "Access Denied" means a Cloudflare firewall (WAF) rule on the site has blocked your request outright.