What steps should I take to restore Moodle from a backup after a 500 error following an upgrade?

If the 500 error persists, restoring from a reliable backup is highly recommended. Ensure your backup includes the Moodle code, database, and any uploaded files. After restoring, check file permissions, verify the database connection details in `config.php`, and test Moodle to see if the error is resolved. If the backup is corrupted, you may need to attempt a different backup or a fresh installation.