Unfortunately, Plesk doesn’t seem to have a way to upgrade MariaDB using the components in the control panel.

Attempts to add this feature didn’t work for me either despite their claims

Hint: you can add an extension from the Plesk interface named Panel.ini Editor if you want to try your luck:

The following official article on Plesk doesn’t work either

https://support.plesk.com/hc/en-us/articles/12388091703703

It results in an error like this:

The repository 'https://dlm.mariadb.com/repo/maxscale/latest/apt bionic Release' does not have a Release file.

Failed to add trusted package signing keys

The Solution:

1. First create backups of all databases as .sql dump:

   MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysqldump -u admin --verbose --all-databases --routines --triggers > /tmp/all-databases.sql

2. Create a backup of all MySQL/MariaDB data (this is different from the above — it copies the entire current mysql/mariadb version executables):

   cp -v -a /var/lib/mysql/ /var/lib/mysql_backup

Then, follow this instead: https://mariadb.org/download/?t=repo-config&d=18.04+LTS+%22bionic%22&v=11.2&r_m=knownhost

Make sure you select your right OS version, desired MariaDB version, and a mirror closer to you is preferable.

Hints:
Use cat /etc/*-release to find out your current OS name and version.

Use sudo nano /etc/apt/sources.list.d/mariadb.sources to create a file and paste the contents from second box. Ctrl+X to exit nano and Y to save file.

In the end I finished with some commands from the first article that didn’t work initially. It’s supposed to add the newly installed MariaDB version to Plesk.

6. Start the MariaDB service:

   systemctl start mariadb

7. Upgrade MySQL/MariaDB databases:

   MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -uadmin

8. Restart MySQL/MariaDB service:

   systemctl restart mariadb

9. Execute the following commands to update package version inside Plesk:

   plesk bin service_node --update local
   plesk sbin packagemng -sdf

    

This finally worked…  after a few refreshes Plesk was showing MariaDB Version: 11.2

Let me know how it goes. Good luck!