CAD tip # 10918:

For such cases you may want to set that such forced restart must not occur when there are any logged on users on the particular workstation.

Computer Configuration > Administrative Templates > Windows Components > Windows Update

Double-click on the item "No auto-restart with logged on users for scheduled automatic updates installations" and check its option "Enabled". Exit the dialog with OK/Apply.

Alternatively you can also make the re-prompt interval longer - set the item "Re-prompt for restart with scheduled installations" to Enabled with a value of e.g. 1440 minutes (a whole day).

If you are using a Windows version without a Local Group Policy Editor (e.g. Home), you can perform this setting also in the Registry. Run RegEdit and switch to:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU

Here create a new DWORD key named NoAutoRebootWithLoggedOnUsers and set its value to 1.

If you only need to one-time block the forced restart, you can just stop the "Windows Update" service temporarily (as an Admin). The service will be re-enabled after reboot. From the CMD.exe window, enter the command: