Cannot connect to MySQL server

2002: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

2002: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

Please make sure of the following:

• The MySQL credentials in the config.php file are correct.
• Your MySQL server is installed and is up and running properly.
• If you have recently updated the MySQL credentials in the config.php file, moved your store to another server, or updated the password of your hosting control panel (some control panels update the MySQL password automatically if you change the main password), make sure the MySQL credentials specified in your store's config.php file match the MySQL credentials provided by your hosting.