Plesk inaccessible: SQLSTATE[HY000] [2002] No such file or directory

Symptoms

• Plesk inaccessible with the following error:

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

• The following error is shown in the /var/log/plesk/panel.log:

  [2018-03-24 22:29:12] ERR [panel] SQLSTATE[HY000] [2002] No such file or directory:
  0: /opt/psa/admin/externals/Zend/Db/Adapter/Pdo/Abstract.php:144
  Zend_Db_Adapter_Pdo_Abstract->_connect()
  1: /opt/psa/admin/externals/Zend/Db/Adapter/Pdo/Mysql.php:111
  Zend_Db_Adapter_Pdo_Mysql->_connect()
  2: /opt/psa/admin/externals/Zend/Db/Adapter/Abstract.php:460
  ......

• MySQL service cannot be started:

  # systemctl start mysql
  Job for mysql.service failed because the control process exited with error code. See “systemctl status mysql.service” and “journalctl -xe” for details.

• The following error for MySQL in journalctl:

  # journalctl -u mysql
  Mar 24 22:03:00 example.com mysqld[3250]: 2018-03-24T21:03:00.476609Z 0 [ERROR] You have enabled the binary log, but you haven’t provided the mandatory server-id. Please refer to the proper ser
  Mar 24 22:03:00 example.com mysqld[3250]: 2018-03-24T21:03:00.477503Z 0 [ERROR] Aborting

Cause

MySQL misconfiguration. 

Resolution

1. Connect to the server via SSH.
2. Comment out the following lines in /etc/my.cnf:

   #log_bin = /var/log/mysql/mariadb-bin 
   #log_bin_index = /var/log/mysql/mariadb-bin.inde 
   #log_slow_verbosity = query_plan 

3. Start MySQL: 

   # systemctl restart mysql

Additional information

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