Kontact crashing. Akonadi server has trouble. How to repair?

When I start Kontact on opensuse tumbleweed it tells me it can't start the Akonadi Server. More information:

Quote:

me@PC:~> akonadictl start org.kde.pim.akonadictl: Starting Akonadi Server... org.kde.pim.akonadictl: done. Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString) me@PC:~> org.kde.pim.akonadiserver: Starting up the Akonadi Server... org.kde.pim.akonadiserver: database server stopped unexpectedly org.kde.pim.akonadiserver: Database process exited unexpectedly during initial connection! org.kde.pim.akonadiserver: executable: "/usr/sbin/mysqld" org.kde.pim.akonadiserver: arguments: ("--defaults-file=/home/matthias/.local/share/akonadi/mysql.conf", "--datadir=/home/matthias/.local/share/akonadi/db_data/", "--socket=/run/user/1000/akonadi/mysql.socket", "--pid-file=/run/user/1000/akonadi/mysql.pid") org.kde.pim.akonadiserver: stdout: "" org.kde.pim.akonadiserver: stderr: "2021-05-03 18:06:12 0 [Note] /usr/sbin/mysqld (mysqld 10.5.9-MariaDB) starting as process 16523 ...\n" org.kde.pim.akonadiserver: exit code: 6 org.kde.pim.akonadiserver: process error: "Process crashed" org.kde.pim.akonadiserver: Shutting down AkonadiServer... org.kde.pim.akonadicontrol: Application '/usr/bin/akonadiserver' exited normally...

Until a few days ago everything was fine. A bunch of searches in the net brought no enlightening. Any ideas here?