mysql service fails to start/hangs up - timeout (Ubuntu, MariaDB)

Question

I set up my first Ubuntu Server with Ubuntu 16.04, nginx, php7.0, MariaDB, nextcloud and external DynDNS using this tutorial here: Install Nextcloud 9 on Ubuntu 16.04

Answer 1

Moving mysqld to "complain" group was not enough in my case (MariaDB 10.1.21 running on Ubuntu 16.04). I had to fully disable apparmor for mysqld:

sudo ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/ 
sudo service apparmor reload
sudo service mysql restart

Now everything works fine.