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

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

Quick fix: Start the server: sudo systemctl start mysql (or mariadb; macOS brew services start mysql) and check sudo systemctl status mysql / the error log if it won't start. If it is running, find the real socket with sudo ss -xlp | grep mysql and pass it with --socket, or connect over TCP: mysql -h 127.0.0.1 -P 3306 -u root -p.

What it means

When you connect to host localhost, the MySQL client doesn't use TCP — it uses a Unix socket file (default /var/run/mysqld/mysqld.sock on Debian/Ubuntu, /var/lib/mysql/mysql.sock on RHEL, /tmp/mysql.sock on macOS Homebrew). The number in parentheses is the OS error:

• (2) — the socket file doesn't exist: server not running, or a different path.
• (13) — permission denied on the socket or its directory.
• (111) — connection refused: the file exists but nothing is listening (stale socket).

Cause 1: the server isn't running

The most common case. Check and start it:

sudo systemctl status mysql        # or: mariadb, mysqld
sudo systemctl start mysql
sudo systemctl enable mysql        # start on boot

macOS (Homebrew):

brew services list
brew services start mysql

WSL without systemd: sudo service mysql start.

If it isn't installed at all, systemctl status says Unit mysql.service could not be found — install mysql-server or mariadb-server.

Cause 2: the server fails to start

If start fails or the service stops right away, read the log:

sudo journalctl -u mysql -n 50 --no-pager
sudo tail -n 50 /var/log/mysql/error.log

Frequent reasons:

• Disk full — check df -h; MySQL can't write its files.
• Port 3306 already in use by another MySQL/MariaDB instance or container: sudo ss -tlnp | grep 3306.
• Bad config after an edit in /etc/mysql/ — the log names the unknown option.
• Permissions on the data dir after copying/restoring: sudo chown -R mysql:mysql /var/lib/mysql.
• Missing socket directory /var/run/mysqld (it's on tmpfs): sudo mkdir -p /var/run/mysqld && sudo chown mysql:mysql /var/run/mysqld.

Cause 3: client and server use different socket paths

If the server is running, find where its socket actually is:

sudo ss -xlp | grep -i mysql
mysqladmin -u root -p variables | grep socket   # if you can connect another way

Then point the client at it:

mysql -u root -p --socket=/var/lib/mysql/mysql.sock

To make it permanent, set the same path for client and server in my.cnf:

[mysqld]
socket=/var/run/mysqld/mysqld.sock

[client]
socket=/var/run/mysqld/mysqld.sock

For PHP, set pdo_mysql.default_socket / mysqli.default_socket in php.ini to the same path.

Cause 4: MySQL is in Docker, client on the host

A container's socket isn't visible on the host. localhost makes the client look for a local socket file and fail. Force TCP to the published port:

mysql -h 127.0.0.1 -P 3306 -u root -p
mysql --protocol=TCP -u root -p

From another container in the same compose network, use the service name as host (e.g. -h db).

Cause 5: permission denied (13)

The user running the client (e.g. a web server) can't access the socket directory. Check:

ls -ld /var/run/mysqld /var/run/mysqld/mysqld.sock

The directory should be traversable (drwxr-xr-x mysql mysql). On SELinux systems, a non-standard socket path also needs the right context.

Last updated 2026-10-30.