Upgrade from 16LTS to 18LTS breaks Apache2

Just upgraded one of our servers from 16-LTS to 18-LTS, which broke Apache (the website that worked prior to the upgrade now displays
-----------
setStart($startTime, $startMem)->mark('afterLoad') : null; // Instantiate the application. $app = JFactory::getApplication('site'); // Execute the application. $app->execute();
-----------
Nothing really in any of the logs that sheds light on what may be wrong
After further investigation I found the Apache php7_module seems to have has disappeared during the upgrade . I fixed the issue on this one server by following the instructions from here https://www.vultr.com/docs/how-to-install-and-configure-php-70-or-php-71-on-ubuntu-16-04 which fixed the issue

I just upgraded another server, and and have found a similar issue. This time the php7_module is there (although the version of php is now 7.2) , but the website is down with now indication as to what is wrong