MySQL/MariaDB fails to start: Upgrade after a crash is not supported

Symptoms

• MySQL/MariaDB service fails to start.

• The following error messages appear in the logs /var/log/mysql/error.log or /var/log/mariadb/mariadb.log:

  InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes
  InnoDB: than specified in the .cnf file 0 536870912 bytes!
  [ERROR] Plugin 'InnoDB' init function returned error.
  [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.

  ---

  [ERROR] InnoDB: Upgrade after a crash is not supported. This redo log was created before MariaDB 10.2.2. Please follow the instructions at https://mariadb.com/kb/en/library/upgrading/
  [ERROR] InnoDB: Plugin initialization aborted with error Generic error
  [Note] InnoDB: Starting shutdown...
  [ERROR] Plugin 'InnoDB' init function returned error.
  [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
  [Note] Plugin 'FEEDBACK' is disabled.
  [ERROR] Unknown/unsupported storage engine: InnoDB
  [ERROR] Aborting

• Errors like below may be shown when running the MySQL/MariaDB check:

  # mysqlcheck -uadmin -p`cat /etc/psa/.psa.shadow ` -A
  ...
  wordpress_terms
  Error : Unknown table engine 'InnoDB'
  error : Corrupt
  wordpress_usermeta
  Error : Unknown table engine 'InnoDB'
  error : Corrupt
  wordpress_users
  Error : Unknown table engine 'InnoDB'
  error : Corrupt

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

  ERROR: Zend_Db_Statement_Exception: SQLSTATE[42000]: Syntax error or access violation: 1286 Unknown table engine 'InnoDB' (Pdo.php:234)

Cause

The InnoDB files ib_logfile0 and ib_logfile1 are corrupted.

Resolution

1. Connect to a Plesk server via SSH.

2. Stop MySQL/MariaDB server:

   # systemctl stop mysql || systemctl stop mariadb || systemctl stop mysqld

3. Rename the corrupted ib_logfile files:

   # mv /var/lib/mysql/ib_logfile0 /var/lib/mysql/ib_logfile0.bak
   # mv /var/lib/mysql/ib_logfile1 /var/lib/mysql/ib_logfile1.bak

4. Start MySQL/MariaDB server:

   # systemctl start mysql || systemctl start mariadb || systemctl start mysqld