1. Check the error log for the MySQL 129 error:

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

2. Check the MySQL configuration file for any misconfigurations:

$ cat /etc/mysql/my.cnf

3. Check the MySQL user permissions:

$ mysql -u root -p
mysql> SELECT User, Host, Password FROM mysql.user;

4. Check the MySQL database tables:

mysql> SHOW TABLES;

5. Check the MySQL database privileges:

mysql> SHOW GRANTS FOR 'username'@'localhost';

6. Restart the MySQL service:

$ sudo service mysql restart

7. Use an automated database observability tool to monitor and fix the MySQL 129 in question. Automated database observability tools can provide real-time visibility into the performance and health of your database, allowing you to quickly identify and fix any issues that arise. They can also provide detailed insights into query performance, allowing you to optimize your database for better performance.