I decided to let the update process overwrite any config files that I had edited, knowing that I had a few that might need updating.
There was one issue with Apache2 where the newest version of PHP wasn’t linked in the config files for Apache. The problem was that there were two the load files—one for 7.2 and one for 7.4. I deleted the one for 7.2 and renamed the one for 7.4 then reloaded the modules and restarted Apache. That seems to have worked.
sudo rm /etc/apache2/mods-available/php7.2.load
mv /etc/apache2/mods-available/php7.2.conf /etc/apache2/mods-available/php7.4.conf
sudo a2enmod php7.4Mail stopped working, but that’s because Dovecot didn’t know where to find the SSL certificates from Let’s Encrypt and where to put the mail. I followed the directions in a previous post and it works now.