NCP v1.23.1 Update -> 18.0.2 fails: mysql unknown variable log_error [solved]

Hello all,

Fully working NCP v1.23.1 fails to update nc:

[ nc-update-nextcloud ]
Current Nextcloud version
Available Nextcloud version 18.0.2
mysql: unknown variable 'log_error=/var/log/mysql/mariadb.err'

System Info
NextCloudPi version	v1.23.1
NextCloudPi image	NextCloudPi_12-20-19
distribution	Raspbian GNU/Linux 10 \n \l
automount	yes
USB devices	sda sdb
datadir	/media/myCloudDrive/ncdata
data in SD	no
data filesystem	btrfs
data disk usage	257G/932G
rootfs usage	13G/59G
swapfile	/var/swap
dbdir	/media/myCloudDrive/mysql
Nextcloud check	ok
Nextcloud version
HTTPD service	up
PHP service	up
MariaDB service	up
Redis service	up
Postfix service	up
internet check	ok
port check 80	open
port check 443	open

What can I do?

Found the solution myself: /etc/mysql/my.cnf contained the line log_error=/var/log/mysql/mariadb.err which i commented out and then the update went smoothly.