Before a procedural walkthrough ships, every step runs on at least two brands when the task is host-specific, or twice on the same stack on different days when it is not. Console errors are captured, UI label drift between regions is noted, and copy is revised the moment a vendor moves a button. Screenshots and paths are spot-checked quarterly. Security-sensitive actions (DNS, SSL, billing) trigger recovery-option checks plus links to the host's own documentation for authoritative wording.
In wp-config.php set WP_DEBUG_LOG true and WP_DEBUG_DISPLAY false to capture fatals without showing errors to visitors. Revert after fixing.
Read wp-content/debug.log and your hosting error log in cPanel/hPanel for the first fatal stack trace.
Rename wp-content/plugins to plugins-old via FTP/SFTP. If the site loads, rename back and re-enable plugins one by one.
Rename your active theme folder to force Twenty Twenty-Five. confirms theme vs plugin issues.
Add define('WP_MEMORY_LIMIT', '256M'); in wp-config.php if logs show allowed memory exhausted. then find the greedy plugin.
In hosting panel select PHP 8.1 or 8.2 compatible with your plugins; incompatible PHP causes opaque 500s.
If core files were edited, restore clean wp-admin/wp-includes from a backup or official zip.