Completely Fixing MySQL/MariaDB Connection Errors — ERROR 1045 · Can't connect · socket

# Try connecting with the root password
mysql -u root -p

# Specific user
mysql -u myuser -p mydb

# Stop the MySQL service
sudo systemctl stop mysql

# Start without authentication
sudo mysqld_safe --skip-grant-tables &

# Connect, then change the password
mysql -u root

-- MySQL 5.7 and earlier
UPDATE mysql.user SET authentication_string=PASSWORD('new_password') WHERE User='root';
FLUSH PRIVILEGES;

-- MySQL 8.0+
ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_password';
FLUSH PRIVILEGES;
EXIT;

# Restart normally
sudo systemctl restart mysql

-- After connecting as root
SELECT user, host, authentication_string FROM mysql.user;

-- Grant privileges to a specific user
GRANT ALL PRIVILEGES ON mydb.* TO 'myuser'@'localhost' IDENTIFIED BY 'password';
FLUSH PRIVILEGES;

# Check service status
sudo systemctl status mysql      # Ubuntu/Debian
sudo systemctl status mariadb    # MariaDB

# Start if it is not running
sudo systemctl start mysql
sudo systemctl enable mysql

# Confirm the port is actually listening
sudo ss -tlnp | grep 3306

# Check error logs (cause of startup failure)
sudo journalctl -u mysql -n 50
sudo tail -50 /var/log/mysql/error.log

# Find the actual socket file location
sudo find /var/run /tmp -name "*.sock" 2>/dev/null
sudo find /run -name "mysqld.sock" 2>/dev/null

# Check the socket path in the MySQL configuration
sudo grep -r "socket" /etc/mysql/

mysql -u root -p --socket=/tmp/mysql.sock

[client]
socket = /tmp/mysql.sock

-- After connecting as root, create an account that allows remote access
CREATE USER 'myuser'@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON mydb.* TO 'myuser'@'%';
FLUSH PRIVILEGES;

# Check whether MySQL is listening on 127.0.0.1 only
sudo grep -r "bind-address" /etc/mysql/
# bind-address = 127.0.0.1 → change to 0.0.0.0, then restart
sudo systemctl restart mysql

sudo systemctl status mysql          # service status
sudo ss -tlnp | grep 3306            # port listening
sudo tail -30 /var/log/mysql/error.log  # error log
mysql -u root -p --verbose           # verbose connection