MySQL fails to start after an upgrade: mysql.user table is damaged

Symptoms

• MySQL has been upgraded and now fails to start.

• The following error message appears in /var/log/mysqld.log when trying to start MySQL:

  [ERROR] Fatal error: mysql.user table is damaged. Please run mysql_upgrade.

• Plesk is not accessible with the following error message in a browser:

  PLESK_INFO: ERROR: Zend_Db_Adapter_Exception: SQLSTATE[HY000] [2002] No such file or directory
  Additionally, an exception has occurred while trying to report this error: Zend_Exception
  No entry is registered for key 'translate' (Abstract.php:144)

Cause

MySQL 5.1 has been upgraded to 5.5 without running the “mysql_upgrade” command.

Resolution

1. Connect to the Plesk server via SSH.

2. Add the “skip-grant-tables” record to log in to MySQL:

   2.1. Open MySQL configuration file /etc/my.cnf in a text editor. In this example we use the vi editor:

   # vi /etc/my.cnf

   2.2. Add “skip-grant-tables” on a new line under the [mysqld] section:

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

   2.3. Save the changes and close the file.

3. Start MySQL:

   # service mysqld start

   OR

   # service mysql start

4. Complete the MySQL upgrade:

   # mysql_upgrade

5. Remove the line with “skip-grant-tables” from the /etc/my.cnf file.

6. Restart the MySQL service using one of these commands:

   # service mysqld restart

   # service mysql start