Can't connect to local MySQL server through socket

Category: ConnectionVersions: All MariaDB / MySQL versions

🔴 Production Risk Error

HIGH — complete service outage.

What this means

Client error 2002 is returned by the MySQL/MariaDB client library when connecting to localhost (which defaults to a Unix socket connection) and the socket file does not exist or the server is not listening on it. This almost always means the server is not running.

Why it happens

1MariaDB/MySQL server is not running
2Socket file path in client configuration does not match the path the server is using
3Server crashed or was stopped unexpectedly
4Incorrect socket path specified in my.cnf, .my.cnf, or connection string

How to reproduce

Connecting to localhost when the server is stopped.

trigger — this will ERROR

mysql -u root -p
-- Server is not running

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

Fix 1: Start the MariaDB/MySQL service

When the server is not running.

fix

-- On systemd systems:
sudo systemctl start mariadb
sudo systemctl status mariadb

-- On older init systems:
sudo service mysql start

Why this works

Starting the service creates the socket file and begins accepting connections.

Fix 2: Verify and match socket file path

When the server is running but the socket path is mismatched.

fix

-- Find where the server expects the socket:
sudo grep -r 'socket' /etc/mysql/ /etc/my.cnf* 2>/dev/null

-- Connect specifying the socket path explicitly:
mysql -u root -p --socket=/var/lib/mysql/mysql.sock