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. It is often happens after hard reset of the server.

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. Restart the MySQL/MariaDB service:

   # systemctl restart mysql

   # systemctl restart mariadb

4. Switch to the directory with daily dumps:

   # cd /var/lib/psa/dumps

5. Restore the database from the latest daily dump:

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

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

7. Restart the MySQL/MariaDB service:

   # systemctl restart mysql

   # systemctl restart mariadb