Pillar · 40 errors
Hosting & Server Config
Server-level limits — memory, execution time, resource caps — surface as cryptic errors that look like code bugs but are really configuration. Knowing the difference saves hours.
HY000/1040MySQL Error 1040: Too many connections Open client connections reached max_connections, so MySQL refused every new connection until existing ones closed. critical Error 521Cloudflare Error 521: Web Server Is Down Cloudflare reached your origin IP but the TCP connection was refused, so every visitor gets a 521 instead of the site. critical Disk quota exceeded (122)cPanel: Write failed: Disk quota exceeded (122) The account hit 100% of its disk or inode limit, so nothing can be written — sessions, uploads, and database writes all fail. critical 2: No such file or directorynginx 502: connect() to unix:/run/php/php-fpm.sock failed (2: No such file or directory) nginx can't find the PHP-FPM socket file, so PHP pages return 502 — FPM is down or the socket path is wrong. critical cannot get uid for userPHP-FPM: cannot get uid for user '...' — FPM initialization failed PHP-FPM won't start because a pool's user/group references a system account that no longer exists. critical Account SuspendedcPanel: This Account Has Been Suspended The hosting provider has disabled your account at the server level, so every request returns a suspension page instead of your site. critical 503 No server availableHAProxy 503 Service Unavailable: No server is available to handle this request Every backend server in the matched pool is marked DOWN, so HAProxy has nowhere to route the request and returns its own 503. critical DB connectionError establishing a database connection (WordPress) WordPress cannot reach or authenticate to MySQL, so PHP renders a blank page with a single error line instead of your site. critical DNS_PROBE_FINISHED_NXDOMAINDNS_PROBE_FINISHED_NXDOMAIN (domain not resolving) The resolver says the hostname doesn't exist, so the browser never gets an IP to connect to. critical Allowed memory size exhaustedPHP Fatal Error: Allowed Memory Size Exhausted A PHP script asked for more RAM than memory_limit permits, so the engine kills the request mid-execution. high Maximum execution time exceededPHP Fatal Error: Maximum Execution Time of 30 Seconds Exceeded A PHP script ran past the max_execution_time cap, so the engine aborted it before it could finish. high 508508 Resource Limit Is Reached Your hosting account hit its CloudLinux LVE cap for CPU, memory, or processes, so the host throttled the whole site. high upstream sent too big headernginx 502: upstream sent too big header while reading response header PHP-FPM returned response headers larger than nginx's FastCGI buffer, overflowing it and turning the response into a 502. high Primary script unknownPHP-FPM "Primary script unknown" (File not found) nginx handed PHP-FPM a SCRIPT_FILENAME path that PHP-FPM cannot find or read, so it returns a blank File not found. high No input file specifiedNo input file specified (PHP-FPM / cgi.fix_pathinfo) PHP-FPM received a request but couldn't find a real script file at the path the web server handed it. high Premature end of script headersApache 500: End of script output before headers A CGI or FastCGI script exited or printed body content before sending a valid HTTP header line, so Apache returns a 500. high AH01630Apache AH01630: client denied by server configuration Apache 2. high Invalid command 'RewriteEngine'Apache 500: Invalid command 'RewriteEngine' (mod_rewrite) Apache hit a RewriteEngine directive while mod_rewrite was not loaded or . high Too many open filesnginx (24: Too many open files) / worker_connections not enough nginx worker processes ran out of file descriptors under load and started dropping or failing connections with errno 24. high failed to open streamPHP Warning: failed to open stream: Permission denied PHP can't read or include a file because the web-server user lacks filesystem access, often cascading into a fatal include error. high (13: Permission denied)nginx 502: connect() failed (13: Permission denied) while connecting to upstream SELinux is blocking nginx from opening a network connection to your backend, so the proxy_pass fails with permission denied and nginx returns 502. high 406406 Not Acceptable (mod_security) The host's ModSecurity WAF matched a request against a rule and blocked it, returning 406 instead of serving the page. high server reached pm.max_childrenPHP-FPM: server reached pm.max_children setting, consider raising it The FPM pool ran out of worker processes, so new requests queued or died, showing up as slow pages or 502/504 errors. high 98: Address already in usenginx [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use) Another process already holds port 80 or 443, so nginx can't bind its listen socket and refuses to start. high 500.19 (0x80070021)IIS HTTP Error 500.19: Cannot read configuration file / config section locked IIS can't apply web. high ERR_EMPTY_RESPONSEERR_EMPTY_RESPONSE (server closed the connection without sending data) The server accepted the TCP connection then closed the socket before sending a single byte of HTTP response. high (104: Connection reset by peer)nginx 502: recv() failed (104: Connection reset by peer) while reading response header from upstream PHP-FPM (or the app upstream) reset the socket mid-response, so nginx had no headers to read and returned 502. high 110: Connection timed outnginx 504: upstream timed out (110: Connection timed out) while reading response header from upstream nginx waited longer than its read timeout for your backend to send response headers and returned a 504. high AH00485Apache AH00485: scoreboard is full / server reached MaxRequestWorkers setting Every Apache worker is busy, so Apache hit its MaxRequestWorkers ceiling and new requests stall in the queue. high AH00072Apache AH00072: make_sock: could not bind to address [::]:80 (98: Address already in use) Apache fails to start because another process already holds port 80 or 443 on the same address. high EADDRINUSENode.js Error: listen EADDRINUSE: address already in use :::3000 Node can't start its server because another process is already listening on the target port. high EACCESNode.js Error: listen EACCES: permission denied 0.0.0.0:80 A non-root Node process cannot bind a privileged port below 1024 like 80 or 443. high 508508 Resource Limit Is Reached (cPanel / CloudLinux LVE) The account hit a CloudLinux LVE cap — CPU, memory, I/O, or entry processes — so requests are refused. high 502 (13: Permission denied)502 Bad Gateway: connect() to unix:php-fpm.sock failed (13: Permission denied) Nginx or Apache can't open the PHP-FPM Unix socket because the socket's ownership or mode shuts out the web server user. high H12Heroku H12: Request timeout (30s) A web dyno took longer than Heroku's hard 30-second limit to start responding, so the router killed the connection. high upload_max_filesizeThe Uploaded File Exceeds the upload_max_filesize Directive in php.ini Your file is larger than PHP's upload_max_filesize, so the server rejects the upload before it completes. medium 413413 Request Entity Too Large (nginx client_max_body_size) The request body exceeded nginx's client_max_body_size, so nginx rejected it before passing the request to the backend. medium could not build server_names_hashnginx [emerg] could not build the server_names_hash, you should increase server_names_hash_bucket_size A server_name value is too long for nginx's default hash bucket, so the config fails validation and nginx won't start or reload. medium Options not allowed here.htaccess: Option FollowSymLinks not allowed here (500 Internal Server Error) An Options directive in . medium AH00558Apache AH00558: Could not reliably determine the server's fully qualified domain name Apache warns at startup that no global ServerName is set and falls back to a guessed IP. low