How To Fix "Can't Connect To Local MySQL Server Through Socket '/var/run/mysqld/mysqld.sock' (2)" Error?

Checking MySQL server status

To diagnose the MySQL connection problem, check the MySQL server status. Use the systemctl or service commands:

1. For systems using systemd:

   sudo systemctl status mysql

2. For systems using init.d:

   sudo service mysql status

These commands show if the MySQL server is running, stopped, or has issues.

If the server is not running, try to start it:

sudo systemctl start mysql

or

sudo service mysql start

If the server fails to start, check the MySQL log files for error messages. The log files are usually in /var/log/mysql/ or /var/log/mysqld.log.

sudo tail -n 50 /var/log/mysql/error.log

Verifying the MySQL socket file

The MySQL socket file is important for local connections. To verify it:

1. Find the correct socket file path:

   • Check the MySQL configuration file (usually /etc/mysql/my.cnf or /etc/my.cnf)
   • Look for the socket parameter under the [mysqld] section

2. Confirm the socket file exists:

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

   If the file is missing, MySQL is not running or is using a different socket location.

3. Check file permissions:

   • The socket file should belong to the mysql user and group
   • Normal permissions are 0755 or 0777

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

   If the permissions are wrong, fix them:

   sudo chown mysql:mysql /var/run/mysqld/mysqld.sock
   sudo chmod 0755 /var/run/mysqld/mysqld.sock

Starting the MySQL server

To start the MySQL server, use these commands:

For systemd-based systems:

sudo systemctl start mysql

For init.d-based systems:

sudo service mysql start

If the server doesn't start, check the MySQL error log:

sudo tail -n 50 /var/log/mysql/error.log

Common startup issues include:

• Wrong permissions on data directories
• Port conflicts
• Damaged database files

sudo systemctl status mysql

Correcting the MySQL socket file path

To fix socket file path issues:

1. Open the MySQL configuration file:

   sudo nano /etc/mysql/my.cnf

2. Find the [mysqld] section and add or change the socket path:

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

3. Save the file and restart MySQL:

   sudo systemctl restart mysql

For client programs, update their config files or connection settings to use the right socket path.

Resolving socket file permission issues

To fix socket file permission problems:

1. Check current permissions:

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

2. Change ownership and permissions:

   sudo chown mysql:mysql /var/run/mysqld/mysqld.sock
   sudo chmod 0755 /var/run/mysqld/mysqld.sock

For AppArmor or SELinux conflicts:

1. Check AppArmor status:

   sudo aa-status

2. If MySQL is listed, disable AppArmor for MySQL:

   sudo ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/
   sudo apparmor_parser -R /etc/apparmor.d/usr.sbin.mysqld

3. For SELinux, check if it's blocking MySQL:

   sudo ausearch -c 'mysqld' --raw | audit2allow -M my-mysqld
   sudo semodule -i my-mysqld.pp

After applying these fixes, restart MySQL and try connecting again.

Reinstalling MySQL

If other solutions don't work, reinstalling MySQL might fix the problem. Follow these steps:

1. Uninstall MySQL:

   sudo apt-get remove --purge mysql-server mysql-client mysql-common
   sudo apt-get autoremove
   sudo apt-get autoclean

2. Remove MySQL files:

   sudo rm -rf /etc/mysql /var/lib/mysql
   sudo rm -rf /var/log/mysql

3. Install MySQL:

   sudo apt-get update
   sudo apt-get install mysql-server

4. Set up MySQL:

   sudo mysql_secure_installation

This process removes MySQL and installs a new copy, which often fixes persistent issues.

mysqldump -u [username] -p [database_name] > backup.sql

Using TCP/IP connection instead of socket

If socket connections fail, try using TCP/IP:

1. Edit MySQL configuration:

   sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf

2. Find the bind-address line and change it:

   bind-address = 127.0.0.1

3. Restart MySQL:

   sudo systemctl restart mysql

4. Connect using TCP/IP:

   mysql -h 127.0.0.1 -u your_username -p

If you use a firewall, allow MySQL connections:

sudo ufw allow mysql

This method uses network connections instead of sockets, which can help with troubleshooting or as a temporary fix.