Plesk is not accessible: ERROR: Zend_Db_Adapter_Exception: SQLSTATE[HY000] [2002] No such file or directory

Symptoms

• The following error is shown in Plesk:

  ERROR: PleskMainDBException
  MySQL query failed: Incorrect information in file: './psa/misc.frm'

  ---

  ERROR: PleskDBException: Unable to connect to database: mysql_connect(): No such file or directory /var/run/mysqld/mysqld.sock (Error code: 2002). Please check that database server is started and accessible. (Abstract.php:69)

  ---

  ERROR: Zend_Db_Adapter_Exception: SQLSTATE[HY000] [2002] No such file or directory

  ---

  ERROR: Zend_Db_Adapter_Exception: SQLSTATE[HY000] [2002] Connection refused:
  0: /usr/local/psa/admin/externals/Zend/Db/Adapter/Pdo/Abstract.php:144

• Unable to start MySQL/MariaDB service with the following error in /var/log/mysql/error.log, /var/log/mysqld.log, or /var/log/mariadb/mariadb.log:

  InnoDB: Waiting for the background threads to start
  InnoDB: Error: tablespace size stored in header is 3712 pages, but
  InnoDB: the sum of data file sizes is only 3072 pages
  InnoDB: Cannot start InnoDB. The tail of the system tablespace is
  InnoDB: missing. Have you edited innodb_data_file_path in my.cnf in an
  InnoDB: inappropriate way, removing ibdata files from there?
  InnoDB: You can set innodb_force_recovery=1 in my.cnf to force
  InnoDB: a startup if you are trying to recover a badly corrupt database.

• Domain overview page on Domains > example.com is not accessible:

  500 Server Error
  Type SB_Facade_Exception_Generic
  Message
  File generic.php
  Line 33

• Opening WP Toolkit results in the following error:

  Server Error 500 Zend_Db_Adapter_Exception
  Type Zend_Db_Adapter_Exception
  Message SQLSTATE[HY000] [2002]
  No such file or directory
  File Abstract.php Line 144

• Plesk upgrade fails with the following error:

  DATABASE ERROR!!!
  Database psa database found, but version undefined

• A table cannot be properly queried with the SELECT statement:

  select * from db_example.misc;
  ERROR 1033 (HY000): Incorrect information in file: './db_example/misc.frm'

Cause

InnoDB corruption.

Most InnoDB corruptions are hardware-related. Corrupted page writes can be caused by power failures or bad memory. The issue also can be caused by using network-attached storage (NAS) and allocating InnoDB databases on it.