The Delay Restart for scheduled installations machine setting should be configured correctly. Specifies the amount of time for Automatic Updates to wait before proceeding with a scheduled restart. If the status is set to Enabled, a scheduled restart will occur the specified number of minutes after the installation is finished. If the status is set to Disabled or Not Configured, the default wait time is 15 minutes. Fix: (1) GPO: Computer Configuration\Administrative Templates\Windows Components\Windows Update\Delay Restart for scheduled installations (2) KEY: HKLM\Software\Policies\Microsoft\Windows\WindowsUpdate\AU\RebootWarningTimeoutEnabled