Yeah, I did some research before hand and followed this to install the newer version of php.
It’s getting Apache to use 7.3 that I’m having the issue with.
First I did this:
sudo a2dismod php7.0
sudo a2enmod php7.3
sudo service apache2 restart
I then confirmed the selection by running:
sudo update-alternatives --config php
But when apache runs I only get an HTTP Error 500 “This page isn’t working” message.
When I reverse it and go back to 7.0 the site works again.