Product and version: 17 Advanced
OS and version - Windows Server 2012 R2 and Windows 7
Description Advanced 17.03 updater restarts certain systems without prior warning. We have experienced it on a Windows 2012 R2 Server running terminal services, Windows 7 and Windows 10. It didn't reboot Windows Server 2016.
There should be a warning before commencing update that your machine may be restarted.