MySQL service fails to start on a Plesk server: Table ‘mysql.user’ doesn’t exist

Symptoms

MySQL service fails to start with the following error message in /var/log/mysql/error.log:

Can't open and lock privilege tables: Table 'mysql.user' doesn't exist

Cause

The mysql system database is corrupter or is missing.

Resolution

1. Connect to the Plesk server via SSH.

2. Modify the my.cnf file:

   2.1. Open the my.cnf file in a text editor. In this example, we are using the vi editor:

   • on CentOS/RHEL-based distributions

     # vi /etc/my.cnf

   • on Debian/Ubuntu-based distributions

     # vi /etc/mysql/my.cnf

   2.2. Add the skip-grant-tables line under the [mysqld] section:

   [mysqld]
   skip-grant-tables
   <...>

   2.3. Save the changes and close the file.

3. Switch to the directory with daily dumps:

   # cd /var/lib/psa/dumps

4. Restore the database from the latest daily dump:

   # zcat mysql.daily.dump.0.gz | sed -n ‘/– Current Database: `mysql`/,/– Current Database:*/p’ | plesk db

5. Remove the skip-grant-tables directive which was added on step 2.

6. Restart the MySQL/MariaDB service:

   # service mysql restart

   # service mariadb restart