Upgrade of MySQL schema with mysql_upgrade fails with the error: Error: Incorrect database name '#mysql50#.ssh'

Symptoms

• Plesk upgrade fails on upgrading MySQL with the error:

  CONFIG_TEXT: Failed to install 'C:\ParallelsInstaller\parallels\PANEL-WIN_17.5.3\dist-msi-Mic
  rosoft-2003-i386\mysql-admin_mu067.msi': Fatal error during installation. (Error
  code 1603)

  ---

  CONFIG_TEXT: Got error: 1102: Incorrect database name '#mysql50#example.database' when selecting the database

• Upgrade of MySQL schema with mysql_upgrade fails with the error:

  # MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -uadmin
  Looking for 'mysql' as: mysql
  Looking for 'mysqlcheck' as: mysqlcheck
  Running 'mysqlcheck with default connection arguments
  Failed to ALTER DATABASE `#mysql50#.ssh` UPGRADE DATA DIRECTORY NAME
  Error: Incorrect database name '#mysql50#.ssh'
  Running 'mysqlcheck with default connection arguments
  mysqlcheck: Got error: 1102: Incorrect database name '#mysql50#.ssh' when selecting the database
  FATAL ERROR: Error during call to mysql_check for upgrading the tables names.

• There is a folder with dot "." in /var/lib/mysql/ directory.

Cause

Folder with dot (".") in the name in MySQL datadir directory prevents correct execution of mysqlcheck command.

Resolution

Note: MySQL datadir location is defined in my.ini or my.cnf file. By default, it is either /var/lib/mysql (Linux) or "%plesk_dir%\Databases\MySQL\data\" or "%plesk_dir%\MySQL\Data\" (Windows )