A HTTP ERROR 500 means that your PHP code has crashed. Please try enabling display_errors to try and get the error messages from the crash so you know what to fix:
Please note that we are currently upgrading all servers from PHP 7.4 to PHP 8.2. If the server your website is on has been upgraded to PHP 8.2 but your code isn’t compatible, that may explain the crash. You can usually fix that by updating your software.