Warum machst du das als root?
#Edit: Du hast einen MariaDB Service laufen, den du manuell beenden musst.
sudo systemctl stop mariadb ?
CodeFailed to stop mariadb.service: Unit mariadb.service not loaded. invoke-rc.d: initscript mariadb, action "stop" failed. Failed to stop mysql.service: Unit mysql.service not loaded. invoke-rc.d: initscript mysql, action "stop" failed. Attempt to stop MariaDB/MySQL server returned exitcode 5 There is a MariaDB/MySQL server running, but we failed in our attempts to stop it. Stop it yourself and try again!
Da kommt bei mir leider immer:
root@debian:~# systemctl stop mariadb
Failed to stop mariadb.service: Unit mariadb.service not loaded.
root@debian:~# systemctl stop mysql
Failed to stop mysql.service: Unit mysql.service not loaded.