Troubleshooting WordPress 502 Errors
If WP throws 502 errors and pages cannot be accessed, there is generally a problem with the server, either with WP themes or plugins, or with MySQL or PHP-FPM.
- All pages cannot be accessed: server is down, but generally will throw a 504 error – 1 2
- Cannot access /wp-admin/ pages: check MySQL configs, PHPFPM configs, and server resource usage
- Cannot access dynamically generated wp content pages: check plugins and themes