How to setup multiple MySQL in Droplet?

Hi, I try to install a MySQL 8 multiple instances in my Ubuntu 18.x droplet. I configured my.cnf (mysqld groups) , made a second /var/run/mysqld2.pin and mysqld2.sock, created a new datadir (/var/lib/mysql2 inkl. user und usergroup mysql and chmod 777) und try to start the instances.

mysqld_multi start 1 

ok.

And then I try to start the second instance

mysqld_multi start 2

and I always will get the FATAL ERROR “Tried to start mysqld under group [mysqld2], but no data directory was found or could be created. data directory used: /var/lib/mysql2”

and I don’t know why!!!

Be aware - it’s MySQL 8 and mysql_install_db to install the mysql databases is deprecated! Instead I should use mysqld --initialize but it won’t work as well.

Please help!

BR Martin