Pillar · 42 errors
HTTP Status Errors
Every page your server returns comes with an HTTP status code. When that code is in the 4xx or 5xx range, visitors hit a wall instead of your content. These are the most common — and most damaging — website errors, because they stop a page from loading at all.
500500 Internal Server Error A 500 is the server’s way of saying "something broke on my end. critical 502502 Bad Gateway A 502 means one server got an invalid response from another upstream server. critical 503503 Service Unavailable A 503 says the server is temporarily unable to handle the request — usually overload or maintenance. critical Error 522Cloudflare Error 522: Connection Timed Out Cloudflare opened a TCP connection to your origin but never got a reply, so the request times out. critical Error 1016 / 530Cloudflare Error 1016: Origin DNS Error Cloudflare can't resolve your origin's address because the DNS record it needs is missing or points nowhere. critical 500.30HTTP Error 500.30 - ANCM In-Process Start Failure The ASP. critical 502.5HTTP Error 502.5 - ANCM Out-Of-Process Startup Failure IIS started your ASP. critical 404404 Not Found A 404 means the page the visitor requested doesn’t exist at that URL. high 504504 Gateway Timeout A 504 means a gateway waited for the backend and the backend never answered in time. high 403403 Forbidden A 403 means the server understood the request but refuses to authorize it. high Error 524Cloudflare Error 524: A Timeout Occurred Cloudflare connected to your origin fine but the origin took too long to send back an HTTP response. high Error 520Cloudflare Error 520: Web Server Returned an Unknown Error Cloudflare got a response from your origin that it couldn't make sense of — empty, malformed, or oversized. high Error 525Cloudflare Error 525: SSL Handshake Failed With Full (Strict) SSL on, Cloudflare reached your origin but the TLS handshake between them failed. high Error 526Cloudflare Error 526: Invalid SSL Certificate Cloudflare connected over HTTPS but rejected your origin's certificate while running Full (Strict) SSL. high 421HTTP 421 Misdirected Request The server can't serve the requested host on this TLS connection, usually from an SNI vs Host mismatch. high ERR_HTTP2_PROTOCOL_ERRORERR_HTTP2_PROTOCOL_ERROR in Chrome Chrome kills the connection after the server sends a malformed or non-compliant HTTP/2 response. high 500.19HTTP Error 500.19 - Internal Server Error (config data invalid) IIS failed before reaching your app because it couldn't parse or apply the configuration it needs to serve the site. high 410410 Gone The server is declaring a resource permanently removed, a stronger and faster-deindexing signal than 404. high 503.0HTTP Error 503 — The Application Pool Has Been Stopped (IIS) IIS returns 503 because the site's Application Pool is stopped, usually shut down automatically after repeated worker-process crashes. high 508508 Loop Detected The server killed the request because it hit an infinite loop or, on shared hosting, blew past a process/CPU cap. high ERR_RESPONSE_HEADERS_TOO_BIGERR_RESPONSE_HEADERS_TOO_BIG (Chrome Error 325) Chrome aborted the page because the server's response headers blew past its roughly 256KB cap. high ERR_INCOMPLETE_CHUNKED_ENCODINGERR_INCOMPLETE_CHUNKED_ENCODING The chunked response stopped before its terminating zero-length chunk, so Chrome treated the page as cut off. high ERR_CONNECTION_RESETERR_CONNECTION_RESET Something sent a TCP RST and tore down the connection mid-transfer, so the browser shows a hard reset. high Error 530 / 1033Cloudflare Error 530 (1033 Argo Tunnel Error) The hostname routes through a Cloudflare Tunnel but no healthy cloudflared connector is reachable, so the edge has nowhere to send the request. high S3 AccessDeniedAmazon S3 403 AccessDenied (Static Website Hosting) S3 returned a 403 AccessDenied XML body for a static site because the request lacked permission to read the object. high 499HTTP 499 Client Closed Request (Nginx) Nginx logs 499 when the client drops the TCP connection before the upstream finishes responding. medium 419HTTP 419 Page Expired (Laravel CSRF Token Mismatch) Laravel returns 419 when a POST request arrives with a missing, stale, or mismatched CSRF token. medium 431HTTP 431 Request Header Fields Too Large The server rejects the request because its total header size exceeds the configured buffer. medium 403.14HTTP Error 403.14 - Directory Listing Denied IIS got a request for a folder, found no default document to serve, and won't list the folder's contents because directory browsing is off. medium 451451 Unavailable For Legal Reasons The server is refusing the resource because of a legal demand rather than a technical fault. medium 429429 Too Many Requests A client sent too many requests in a short window and the server is throttling it until the rate limit resets. medium 405405 Method Not Allowed The URL exists but the HTTP verb used isn't allowed on that route, most often a POST hitting a GET-only path. medium 409409 Conflict The request clashes with the resource's current state, such as a concurrent edit, duplicate key, or stale version. medium 426426 Upgrade Required The server refuses the request on the current protocol and demands an upgrade, almost always a broken WebSocket handshake through a proxy. medium 428428 Precondition Required The server rejects the write because the client sent no conditional header, forcing you to prove you're editing the version you think you are. medium 412412 Precondition Failed You sent a conditional header but it no longer matches, the resource changed under you between read and write. medium 400 Header Too Large400 Bad Request: Request Header Or Cookie Too Large Nginx rejected the request because the cookies and headers the browser sent are bigger than its header buffers. medium 408408 Request Timeout The server stopped waiting for the client to finish sending the request and closed it with a 408. medium 413413 Payload Too Large (Request Entity Too Large) The server rejected the request because its body exceeded the configured maximum upload size, most often Nginx's 1MB default. medium 414414 URI Too Long The request URL exceeded the server's length limit, usually from oversized query strings or a redirect loop appending parameters. low 416416 Range Not Satisfiable A Range request asked for bytes past the file's actual size, common when resuming a download of a file that changed. low 511511 Network Authentication Required Not your site, the Wi-Fi network is intercepting traffic behind a captive portal until you log in or accept terms. low