MariaDB

## install software-properties-common ##
apt install software-properties-common

## add maria db repository ##
add-apt-repository 'deb [arch=amd64,arm64,ppc64el] http://sfo1.mirrors.digitalocean.com/mariadb/repo/10.3/ubuntu bionic main'

## add GPG Public Key ##
apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8

## update ##
apt update

## Set innodb_fast_shutdown to 0 ##
mysql
SET GLOBAL innodb_fast_shutdown=0;

## stop MariaDB ##
service mariadb stop

## Uninstall the old version of MariaDB ##
apt remove mariadb-server

## Install the new version of MariaDB ##
apt update
apt install mariadb-server

choose N

## start MariaDB ##
service mariadb start

## Run mysql_upgrade ##
mysql_upgrade

## if error ##

nano /etc/mysql/mariadb.conf.d/50-server.cnf

add the line below [mysqld] section.

plugin-load-add = auth_socket.so

service mariadb restart