How to fix ERROR 2002: Can't connect to local MySQL server through socket in MySQL

First, verify that the MySQL server process is actually running. On Linux systems with systemd:

sudo systemctl status mysql

Or on systems using service command:

sudo service mysql status

On macOS with Homebrew:

brew services list | grep mysql

You should see output indicating the service is active/running. If it is not running or shows as inactive, the server needs to be started (see Step 2).

To start the MySQL server, use the appropriate command for your system.

On Linux with systemd:

sudo systemctl start mysql
# or
sudo systemctl start mysqld

On Linux with service command:

sudo service mysql start

On macOS with Homebrew:

brew services start mysql

Wait a few seconds for the server to fully start, then try connecting again:

mysql -u root -p

If the server fails to start, check the MySQL error log (Step 7) for startup errors.

Check if the socket file exists. The default location varies by system and MySQL configuration:

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

Or try the alternate common location:

ls -la /tmp/mysql.sock

If you get "No such file or directory," the socket file does not exist. This confirms the MySQL server is either not running or not creating the socket properly. Start the server and wait a few seconds (Step 2), then check again.

You can also find the socket location by checking the MySQL configuration file:

grep socket /etc/mysql/my.cnf
# or
grep socket /etc/my.cnf
# or on macOS:
grep socket /usr/local/etc/my.cnf

Verify that the socket file and its parent directory have correct permissions. The socket directory should allow the MySQL user to write and the client user to access it:

ls -la /var/run/mysqld/

The permissions should typically be:
- Directory: drwxr-xr-x (755) owned by mysql:mysql
- Socket file: srwxrwxrwx (777) owned by mysql:mysql

If permissions are wrong, fix them:

sudo chown mysql:mysql /var/run/mysqld/
sudo chmod 755 /var/run/mysqld/

If the socket file itself has wrong permissions (rare):

sudo chown mysql:mysql /var/run/mysqld/mysqld.sock
sudo chmod 777 /var/run/mysqld/mysqld.sock

If you are running the client as root, you should have permission. If running as a regular user, ensure that user is in the mysql group:

sudo usermod -a -G mysql your_username

You may need to log out and back in for group membership to take effect.

If you have multiple MySQL configuration files, the client and server may be using different socket paths. Check what the server is actually using:

mysql_config_editor print --all

Or query the running server for the socket path (if you can connect via TCP/IP):

mysql -h 127.0.0.1 -u root -p -e "SHOW VARIABLES LIKE 'socket'"

Then check your client configuration in ~/.my.cnf or /etc/mysql/my.cnf:

cat ~/.my.cnf

Make sure the [client] section specifies the same socket path as [mysqld]:

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

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

If they differ, update the client configuration to match the server's socket path and restart MySQL.

If you cannot resolve the socket issue immediately, you can connect using TCP/IP instead by explicitly specifying the host as an IP address:

mysql -h 127.0.0.1 -u root -p

Or for remote connections:

mysql -h mysql.example.com -u root -p

This bypasses the socket mechanism entirely and uses the network layer. This works if the MySQL server is running and accepting TCP/IP connections on port 3306 (the default). This is a temporary workaround; investigate the root cause using Steps 1-4 for a permanent fix.

You can also update your connection configuration to prefer TCP/IP. In ~/.my.cnf:

[client]
host=127.0.0.1
port=3306
user=root

If the server fails to start or exits immediately, the error log will contain details. Check the MySQL error log:

sudo tail -f /var/log/mysql/error.log

Or on some systems:

sudo tail -f /var/log/mysqld.log

Or on macOS with Homebrew:

tail -f /usr/local/var/mysql/*.err

Common errors include:
- "Address already in use" – MySQL is already running or another service is using port 3306
- "Permission denied" – MySQL user does not have permission to access data directory
- "Corrupted myisam table" – Data files are corrupted; you may need to repair tables
- "InnoDB: Unable to lock" – MySQL data directory is locked by another instance

Search the error message online or consult the MySQL documentation for the specific error code you see.