The update was meant primarily for Windows 10 v1507 and v1511, two Windows 10 versions released in 2015 that are now officially end-of-life.Via: Bleeping Computer
Microsoft was just trying to notify users that they should update to the latest Windows 10 version to receive security updates.
The update was also displayed for Windows 10 v1607 and v1703, even if those OS versions are still supported, but as an optional update alert.
But it appears that KB4023814 misfired for v1703 users with custom update settings and forcibly installed the latest version, v1709.
Microsoft accidentally upgraded users to Windows 10 Fall Creators Update
Posted on Wednesday, Mar 14 2018 @ 11:46 CET by Thomas De Maesschalck