What are the steps required to get HTTP/2 working in ISPConfig with Apache? I assume the server got installed using The Perfect Server so that PHP-FPM and SSL are enabled. Code: sudo a2dismod php7.3 sudo a2dismod mpm_prefork sudo a2enmod mpm_event sudo a2enmod http2 sudo systemctl restart apache2 Is Event the best MPM to choose (instead of Worker)? What are the Pro/Cons of Event/Worker vs. Prefork?
Switch the MPM from Prefork to e.g. Event. The mod_php mode will not work anymore then and it might be that Debian Packages like phpmyadmin and roundcube stop working too, you will have to configure php-fpm as default php handler then.