Fix MySQL "Connection Refused"

Understanding the Error

MySQL is not accepting connections on the specified port/host:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket
ERROR 2003 (HY000): Can't connect to MySQL server on 'host' (111 "Connection refused")

Check if MySQL is Running

sudo systemctl status mysql
sudo systemctl status mariadb

# If not running
sudo systemctl start mysql

Check Port Listening

sudo netstat -tlnp | grep 3306
sudo ss -tlnp | grep mysql

If nothing listening, MySQL isn't bound to any interface.

Check MySQL Bind Address

sudo grep bind-address /etc/mysql/mysql.conf.d/mysqld.cnf
# Or
sudo grep bind-address /etc/my.cnf

If set to 127.0.0.1, MySQL only accepts local connections. For remote access:

bind-address = 0.0.0.0  # Or your server IP

Restart MySQL:

sudo systemctl restart mysql

Firewall Blocking Port 3306

# Check firewall
sudo ufw status
sudo firewall-cmd --list-all

# Allow MySQL port
sudo ufw allow 3306/tcp
sudo firewall-cmd --permanent --add-port=3306/tcp
sudo firewall-cmd --reload

Check MySQL Error Log

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

Socket Connection Issues

If using socket (localhost):

# Find socket location
sudo grep socket /etc/mysql/my.cnf

# Check socket exists
ls -la /var/run/mysqld/mysqld.sock

# Specify socket in connection
mysql -S /var/run/mysqld/mysqld.sock -u root -p

Resource Exhaustion

Disk full or memory issues:

df -h
free -h
dmesg | tail -20