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

This error message indicates that the MySQL server on the local machine is not running or is not configured properly. The MySQL server uses a Unix socket file located at /var/lib/mysql/mysql.sock to communicate with client applications. If this socket file is missing or inaccessible, client applications cannot connect to the MySQL server.

To resolve this error, try the following steps:

1. Check if MySQL server is running: Open a terminal window and enter the command 'systemctl status mysql.service'. If the output shows that the service is not running, try starting it using the command 'systemctl start mysql.service'.

2. Check the socket file path: Verify that the socket file is located at /var/lib/mysql/mysql.sock. If the file is missing or located elsewhere, update the MySQL configuration file (/etc/mysql/my.cnf) to use the correct path for the socket file.

3. Check file permissions: Verify that the socket file has the correct permissions that allow the MySQL server to access it. The file should be owned by the mysql user and group with read and write permissions for the owner and group. Use the command 'ls -l /var/lib/mysql/mysql.sock' to check the file permissions.

4. Restart MySQL server: If you have made changes to the MySQL configuration file, restart the MySQL server using the command 'systemctl restart mysql.service'.

If none of these steps resolve the issue, there may be a more serious problem with the MySQL server installation or configuration. Consider checking the MySQL error log (/var/log/mysql/error.log) for more information about the error.