Hey, good to hear it! The wiki has been updated with your changes. Please check if it’s correct, and feel free to contribute to with your corrections.
#4 Maybe it was the libjpeg-turbo library, which was not used by default by older versions of zoneminder.
Back to issue #1: (cc/ @davidep @filippo_carletti @giacomo)
Zoneminder systemd service expects mariadb.service to be running, but fails to start it because the socket is being used by mysqld.service.
On a new minimal Centos installation it’s working without problems, as there’s only mariadb.service (no myslqd.service).
On NethServer there are mariadb and mysqld services. I can be wrong but think this is part of the issue (as well as it is/was for sogo).