Changing the guacamole MySQL User Password

From an SSH shell execute the following commands to change the MySQL user password:

mysql -u root -h localhost -p'<root password>'
USE guacamole;
SET PASSWORD FOR 'guacamole'@'localhost' = PASSWORD('<new password>');

Now modify /etc/guacamole/guacamole.properties ensuring you update the value for “mysql-password: <password>”

# MySQL properties
mysql-hostname: localhost
mysql-port: 3306
mysql-database: guacamole
mysql-username: guacamole
mysql-password: <password>

Finally restart tomcat8

systemctl restart tomcat8