What are the initial troubleshooting steps to diagnose an HTTP Error 500 in cPanel for a PHP application?

Begin by checking the cPanel "Errors" log (under the Metrics section) for specific error messages, which often pinpoint the exact line or file causing the issue. Next, temporarily disable the `.htaccess` file by renaming it (e.g., to `htaccess_bak`) to rule out configuration errors. Verify that file and directory permissions are correct (typically 644 for files and 755 for directories). If recent changes were made, revert them to see if the error disappears.