Plesk upgrade or databases backup fails: mysqldump: unknown variable

Symptoms

• Unable to upgrade Plesk, the process fails with the error below:

  /usr/bin/mysqldump: unknown variable 'bind-address=203.0.113.2'
  ERROR while trying to backup MySQL database

  ---

  /usr/bin/mysqldump: unknown variable 'sql-mode=NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION'

  ---

  /usr/bin/mysqldump: unknown variable 'max_connections=150'

• Creation of the database backup fail with the same error.

Cause

The incorrect directive is set under [mysqldump] section in the MySQL/MariaDB configuration file.

Resolution

1. Log into the server via SSH.

2. Execute the command below to find the MySQL/MariaDB configuration file:

   # (ls -l /etc/my.cnf || ls -l /etc/mysql/my.cnf) 2>> /dev/null | awk {'print $NF'}

   Note: in the example below the name of the found file will be /etc/my.cnf, in your case it also  can be /etc/mysql/my.cnf.

3. Create a backup for found file on the previous step:

   # cp -pr /etc/my.cnf{,.backup}

4. Using the vi text editor open the /etc/my.cnf found on the step №2.
5. Find and remove the line with directive reported during the Plesk upgrade process from the [mysqldump] section.
6. Save the changes
7. Run the command below to restart MySQL/MariaDB service:

   # (systemctl restart mysql || systemctl restart mariadb || systemctl restart mysqld) 2>/dev/null