Linux: The unit file, source configuration file or drop-ins of MYSERVICE.service changed on disk

 An error while trying to start a service:

root@MySQL:/lib/systemd/system# systemctl status MYSERVICE.service

Warning: The unit file, source configuration file or drop-ins of MYSERVICE.service changed on disk. Run 'systemctl daemon-reload' to reload units.

Solution:

As written: run 'systemctl daemon-reload' to reload units.

systemctl daemon-reload

This command is required every time the .service file is changed.