Unknown Collation Error in Plesk: How to Upgrade MariaDB

Updated: 28 September 2026 · Applies to: Plesk Obsidian on AlmaLinux, Rocky Linux, RHEL, Ubuntu and Debian, and on CloudLinux 8 and 9 with MySQL Governor

When you import or copy a WordPress database into Plesk, the import can stop with an error like this:

ERROR 1273 (HY000) at line 25: Unknown collation: 'utf8mb4_unicode_520_ci'

The database was created on a newer database server that knows a collation the server in Plesk does not. The same happens with utf8mb4_0900_ai_ci from MySQL 8, which MariaDB accepts only from version 11.4.5 (we checked it on MariaDB 11.8). The fix is to upgrade the database server, or to convert the collation in the dump file. This article replaces an older guide for MariaDB 10.1 on CloudLinux 7, which is no longer supported by CloudLinux's MySQL Governor.

1. Check the current version

mysql -V

MariaDB 5.5 and 10.0 are long out of support. Current Plesk versions support MariaDB long-term releases such as 10.6, 10.11 and 11.4; check Plesk's list of supported versions before you choose one.

2. Back up everything first

The upgrade affects every site on the server, and the websites are unavailable while it runs. Choose a quiet time and take a full dump and a copy of the data folder:

MYSQL_PWD=$(cat /etc/psa/.psa.shadow) mysqldump -u admin --all-databases --routines --triggers --events > /root/all-databases.sql
systemctl stop mariadb
cp -a /var/lib/mysql /var/lib/mysql.backup
systemctl start mariadb

Make sure the disk has room for both copies.

3a. Plesk on AlmaLinux, Rocky Linux, RHEL, Ubuntu or Debian

Use Plesk's built-in upgrade: go to Tools & Settings > Database Servers, click Upgrade now, choose the target version and follow the checks. Plesk upgrades MariaDB, adjusts the configuration and verifies the result. It takes about ten minutes. Keep SSH access open during the upgrade in case you need to act.

From MariaDB 5.5, the first run goes to MariaDB 10.5; run it again to reach a current long-term release.

3b. Plesk on CloudLinux with MySQL Governor

The built-in Plesk upgrade is not available on CloudLinux. There, MySQL Governor installs the database server from CloudLinux's repositories. Upgrade one major version at a time (for example 10.6, then 10.11, then 11.4):

/usr/share/lve/dbgovernor/mysqlgovernor.py --mysql-version=mariadb1011
/usr/share/lve/dbgovernor/mysqlgovernor.py --install

The values are mariadb106, mariadb1011 and mariadb1104 for MariaDB 10.6, 10.11 and 11.4 (11.4 is not available on CloudLinux 7). Then update the system tables and let Plesk detect the new version:

MYSQL_PWD=$(cat /etc/psa/.psa.shadow) mariadb-upgrade -u admin
systemctl restart mariadb
plesk bin service_node --update local
plesk sbin packagemng -sdf

Upgrades from MySQL 8 to MariaDB are not supported by MySQL Governor. If you are unsure which version your server can move to, ask CloudLinux support before you start.

4. Check the result

• mysql -V shows the new version, and Plesk shows it in Tools & Settings > Database Servers.
• Open a few websites and check that they load.
• Import the dump that failed before.

Alternative: convert the collation in the dump

If you cannot upgrade now, change the unknown collation to one the server supports, in a copy of the dump:

sed -e 's/utf8mb4_0900_ai_ci/utf8mb4_unicode_ci/g' -e 's/utf8mb4_unicode_520_ci/utf8mb4_unicode_ci/g' site.sql > site-fixed.sql

This changes how the database sorts and compares text in some languages, which is usually fine for WordPress. Upgrading the database server is still the better long-term fix.

Need help?

Our Plesk server management team can plan and run the upgrade for you.

Official documentation: Plesk: upgrading MariaDB to the current long-term version and CloudLinux OS components: MySQL Governor.