(Solved) Upgrade from MySQL to MariaDB breaks Akonadi

Hello!

When you upgrade MySQL to MariaDB, Akonadi won't start any longer. This 
happens on Kubuntu, but it could also happen somewhere else.

The package mariadb-server needs to be installed for MariaDB (again, on 
(K)Ubuntu).

This replaces MySQL (mysql-server-core-5.7 and mysql-client-core-5.7). After 
that, Akonadi won't start any longer. "aconadictl start" outputs a lot of 
messages.

The problem can be repaired by doing this, after the installation of MariaDB:

akonadictl stop
rm -r ~/.local/share/akonadi
akonadictl start

Bye,
Volker