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MySQL Connection Issues
- Check if the MySQL service is running:
- On Linux, use `sudo systemctl status mysql` or `sudo service mysql status`.
- On Windows, use `services.msc` and look for MySQL service status.
- Verify MySQL is listening on the expected port (default 3306):
- Use `netstat -tuln | grep 3306` on Linux.
- On Windows, use `netstat -an | find "3306"`.
- Check the MySQL error log for specific error messages:
- Typically found in `/var/log/mysql/error.log` on Linux.
- On Windows, check the MySQL installation directory, often within `ProgramData\MySQL\MySQL Server X.Y\data`.
- Test connection to MySQL using the command line:
- `mysql -u username -p -h localhost`
- If running on a remote server, ensure the firewall isn't blocking MySQL's port (3306 by default):
- For Linux, use `sudo ufw status` to see if the port is allowed, or `sudo iptables -L` to check firewall rules.
- On Windows, check the Firewall settings in Control Panel.
- Confirm that the MySQL user has access from your IP address or `%` (any host):
- Connect to MySQL and run `SELECT host, user FROM mysql.user WHERE user = 'your_username';`
- Check for max_connections limit:
- Connect to MySQL and run `SHOW VARIABLES LIKE "max_connections";`
- Inspect server's memory and CPU usage:
- On Linux, use `top` or `htop` to monitor real-time usage.
- On Windows, use Task Manager.
- Verify disk space is sufficient:
- On Linux, use `df -h`.
- On Windows, check in File Explorer or use `chkdsk`.
- If applicable, check if the MySQL port is open and listening to external connections, not just localhost:
- Run `SELECT host FROM informationschema.processlist WHERE user='yourusername';` to see where connections are coming from.
These actions can help identify and potentially resolve the connection issue with the MySQL database.
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