The problem
The public site showed a WordPress critical-error screen after recent updates. The owner could not rely on wp-admin, and guessing at plugin toggles risked making the only working copy harder to recover.
The repair path
Preserve the best available copy
Before changing the broken installation, the files and database need a backup or an existing backup needs to be verified. That gives the repair a rollback path if the first visible symptom is not the only problem.
Read the real failure
Critical-error screens are usually a wrapper around a PHP fatal error, memory failure, incompatible plugin, theme function, damaged update, or PHP-version mismatch. Server logs, WordPress debug output, and file timestamps help identify the failing layer.
Restore service and verify
The fix can include disabling a failing plugin safely, replacing damaged core files, adjusting PHP compatibility, correcting permissions, clearing maintenance mode, or restoring a known-good component. Afterward, the public pages, login screen, admin area, forms, and update state need to be checked.
Why this matters
A site can appear fixed while still carrying the same outdated plugin, incompatible PHP setting, or missing backup that caused the failure. The handoff should explain what failed and what should be watched next.