Windows Server 2016 automatically restart

We've had a 2016 reboot on critical servers after updates! Even worse, during operating hours! We have a group policy to prevent an automatic restart of the servers if a new update(s) is available:

• Configure automatic updating: 3 - Auto download and notify for install

These settings just working fine on the 2012R2 servers, but all server 2016 restarted without administrator consent. The event log contains this entry:

The process C:\WINDOWS\system32\svchost.exe ("ServerName") has initiated the restart of computer "ServerName" on behalf of user NT AUTHORITY\SYSTEM for the following reason: Operating System: Service pack (Planned) Reason Code: 0x80020010 Shutdown Type: restart

If you set three policies in GPO like below:

1- No auto-restart with logged on users for scheduled automatic updates installations.
2- Re-prompt for restart with scheduled installations.
3- Configure automatic updating: 3 – Auto download and notify for install.

So,

the no auto-restart with logged on users for scheduled automatic updates installations policy behaviour changed in Windows 10/Windows Server 2016.

Policy no auto-restart with logged on users for scheduled automatic updates installations only applies when Configure Automatic Updates is set to option 4-Auto download and schedule the install.

At the same time, option 4-Auto download and schedule the install only valid if values exist for ScheduledInstallDay and ScheduledInstallTime.

So, although you have configured to not re-start when there are log on users, automatically re-start will still happens at scheduled time.

Below are relate articles, just for you to have an further understanding.

https://docs.microsoft.com/en-us/windows/deployment/update/waas-restart

https://msdn.microsoft.com/en-us/library/dd939844(v=ws.10).aspx

Pejvak you can choose option 2 for Configure automatic updating According to this link to solve the problem too.