Symptoms

• After upgrading MySQL/MariaDB, the service fails to start with the following error message in /var/log/mariadb/mariadb.log or /var/log/mysql/error.log:

  [Note] InnoDB: Starting shutdown...
  [ERROR] Plugin 'InnoDB' init function returned error.
  [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
  [Note] Plugin 'FEEDBACK' is disabled.
  [ERROR] Unknown/unsupported storage engine: InnoDB
  [ERROR] Aborting

• The same error may appear during Plesk upgrade or update.

Cause

The mariadb/mysql service was not stopped properly after an upgrade.

Resolution

1. Connect to the Plesk server via SSH.

2. Stop the service properly using the command::

   # mysqladmin -uadmin -p`cat /etc/psa/.psa.shadow` -h127.0.0.1 –protocol=tcp shutdown

3. Start the MySQL/MariaDB service:

   # service mysql restart

   # service mariadb restart