Best answer by Flood and Flood's wife
Agreed, sadly the notification has & continues to confuse some Kaspersky subscribers.
The notification Restart required to complete application version upgrade - Reboot, is for Kaspersky software, whenever there is a new Kaspersky application version & or a new Kaspersky application patch.
The “explanation” is documented in old Kaspersky Internet Security 20 release notes documentation, unfortunately it comments on patches, not versions, however, the advisory applies to both:
- To complete the patch installation successfully, computer reboot is required. If you don't reboot the computer in seven days after the application receives the patch, the icon in the notification area will turn red.
Similar advisory is in KIS21 documentation, in the Installing an update package section:
- When an update package (patch) is received, Kaspersky Internet Security installs it automatically. To complete the installation of an update package, you must restart the computer. Until the computer is restarted, the application icon in the notification area is red, and the Kaspersky Internet Security Notification Center window displays a prompt to restart the computer.