Please be aware I have no expertise of my own with NextcloudPi, unfortunately. However, some general advice in the following.
Your system may be without the nginx server and happily away from the a.m. ‘NGINX/php-fpm’ issue. Check for your active webserver with:
sudo systemctl status apache2
This should show your Apache 2.4 on the job or some other info.
You may consult the below article for background information.
Why NextCloudPi uses Apache and not Nginx
Consult the NCP docs on the project website and the NCP release section at GitHub:
There is an article as of August 2019 available giving some overview and specific advice on NCP updates on:
Apparently, one should follow a three stages procedure for a more thorough NextcloudPi updates / system migration:
In order to upgrade issue the following commands
Should the upgrade fail at some Debian package, you can issue
ncp-dist-upgrade again after fixing it to complete the process.
Your goal should be a PHP 7.3 install. Apparently, the NCP update procedure should ensure for everything in the right place.
However, please be aware to avoid the apt update command usual to other Linux flavours as NCP provides the a.m. special commands
ncp-dist-upgrade specifically. Mixing NCP packages with standard packages would bring you some hassle and would destroy the good efforts of the NCP project on your install, I presume.
Furtherly, you may consult the NC 16 php.ini configuration notes in the Nextcloud docs.
Please be aware you currently are in the ‘news’ category. There may be some better place to ask for help on your issues in this NC forum available at:
Hope this helps.
BTW a little ACK to my comment (i.e. click on the heart icon ) would show you are satisfied. This could be a kind gesture and would motivate me like authors of other advice to continue in seeking to help…