How to Fix 500 Internal Server Error

Common Causes and Fixes

1. Corrupted htaccess

Rename .htaccess to .htaccess_bak temporarily. If site works, the issue is in .htaccess. Regenerate via WordPress Settings - Permalinks - Save.

2. PHP Memory Limit

Add to wp-config.php: define WP_MEMORY_LIMIT 256M

3. Faulty Plugin

Rename wp-content/plugins to plugins_bak. Re-enable plugins one by one to find the culprit.

4. Wrong Permissions

Folders: 755, Files: 644, wp-config.php: 640

5. Check Error Logs

cPanel Error Logs section, or enable WP_DEBUG in wp-config.php and check wp-content/debug.log.