If you are using ubuntu or apparmor you should permit this change in apparmor.
Edit /etc/apparmor.d/usr.sbin.mysqld and change /var/lib/mysql with the new DATADIR.
It should work.
If you are using ubuntu or apparmor you should permit this change in apparmor.
Edit /etc/apparmor.d/usr.sbin.mysqld and change /var/lib/mysql with the new DATADIR.
It should work.