Solution for Plesk Panel 500 Plesk\Exception\Database Error

Recently, we encountered this error on one of our servers, and here’s how we resolved it.

Additional Errors Displayed on Screen

Job for mariadb.service failed because the control process exited with error code. See “systemctl status mariadb.service” and “journalctl -xe” for details.
DB query failed: SQLSTATE[HY000] [2002] No such file or directory

The server is running on CentOS, and we are connecting via SSH.
Open the MySQL configuration file by running:

vi /etc/my.cnf

Add the following line to the my.cnf file:

open_files_limit = 1024000

Save the changes and restart the MySQL service:

systemctl restart mysql

Alternatively, you can reboot the server if restarting the service doesn’t work:

reboot

This resolved the issue for us.