Unable to start MySQL/MariaDB after changing the innodb_log_file_size parameter: log file ./ib_logfile0 is of different size

Symptoms

• Plesk is not accessible with one of the following error messages in a web-browser:

  PLESK_INFO: Server Error
  500
  Zend_Db_Adapter_Exception
  SQLSTATE[HY000] [2002] No connection could be made because the target machine actively refused it.

  PLESK_INFO: Server Error
  500
  Zend_Db_Adapter_Exception
  SQLSTATE[HY000] [2002] No such file or directory

• Websites that use MySQL/MariaDB databases do not work or work improperly.
• MySQL/MariaDB fails to start after setting up the innodb_log_file_size parameter in MySQL/MariaDB configuration:

  • The error message on Linux:

    MYSQL_LIN: start: Job failed to start

    MYSQL_LIN: Job for mariadb.service failed because the control process exited with error code. See "systemctl status mariadb.service" and "journalctl -xe" for details.

  • The error message on Windows Server:

    PLESK_INFO: The MySQL service fails to start with the error 1067 "The process terminated unexpectedly"

• The following messages appear in the MySQL/MariaDB logfile:

  • Logfile location on Linux: /var/log/mysql/error.log (or /var/log/mariadb/mariadb.log if MariaDB is installed)
  • Logfile location on Windows Server: %plesk_dir%MySQL\Data\<SERVER_NAME>.err

  CONFIG_TEXT: InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes
  InnoDB: than specified in the .cnf file 0 536870912 bytes!

Cause

After changing the innodb_log_file_size value in MySQL/MariaDB configuration, old log files ib_logfile0 and ib_logfile1 still exist with a different size on the server.

Resolution

Follow steps from this KB article:

• How to change the value of innodb_log_file_size in MySQL/MariaDB