A page shows 502
Trace the browser, CDN, gateway, nginx, and upstream app in order.
FaultForge
Troubleshooting paths for real web failures: 404 routes, 500 crashes, 502 gateways, DNS lookup errors, WordPress database failures, nginx upstream issues, and Chrome page crashes.
What are you trying to fix?
WordPress cannot load
Check plugins, PHP errors, database access, and recent changes.
The domain does not resolve
Compare resolvers, flush local cache, and verify authoritative records.
A page returns 500
Use logs and safe rollback steps before editing production config.
Topics
DNS Errors and Troubleshooting
Troubleshoot DNS errors by checking NXDOMAIN symptoms, nameservers, A and CNAME records, resolver cache, propagation, and browser messages.
HTTP Errors and Troubleshooting
Understand HTTP errors such as 404, 500, and 502, then choose the right checks for routes, logs, proxies, redirects, and upstream servers.
Database Errors and Troubleshooting
Diagnose website database errors involving WordPress, MySQL, MariaDB, credentials, server health, migrations, and connection limits.
Platforms
Featured Error Codes
502 Bad Gateway
Diagnose a 502 Bad Gateway by checking the proxy, CDN, upstream app, PHP-FPM, timeouts, and server logs before changing DNS.
404 Not Found
Diagnose a 404 Not Found by checking the URL, deleted files, broken routes, redirects, permalinks, and server configuration.
500 Internal Server Error
Find the cause of a 500 Internal Server Error by checking logs, recent deploys, plugins, PHP failures, permissions, and rollback options.
DNS_PROBE_FINISHED_NXDOMAIN
Resolve DNS_PROBE_FINISHED_NXDOMAIN by checking domain records, nameservers, resolver cache, DNS propagation, and browser/network settings.
Error Establishing a Database Connection
Fix the WordPress database connection error by checking wp-config.php, database credentials, MySQL/MariaDB health, and hosting changes.
Aw, Snap! in Chrome
Fix Chrome Aw, Snap! crashes by isolating extensions, profile corruption, cache issues, hardware acceleration, and device-specific problems.
Guides
Check access and error logs for HTTP failures
Learn how to inspect access logs, error logs, status codes, timestamps, upstream failures, and recent changes during HTTP outages.
Trace 502 through proxy, CDN, and upstream layers
Trace a 502 Bad Gateway across browser, CDN, reverse proxy, origin server, upstream app, and logs to find the failing layer.
Verify nginx upstreams, sockets, and proxy_pass targets
Check nginx upstream definitions, Unix sockets, proxypass targets, service health, permissions, and logs when nginx returns 502.
Repair WordPress database settings in wp-config.php
Check and repair WordPress database settings in wp-config.php, including database name, user, password, host, charset, and table prefix.