There is already a reply from Microsoft - this may be fixed in next month patch cycle!
maybe we should all be happy that it did *not* install, as there may be another issue arising too...
Even though MS says it does install, but just brings a "false" error message up, on my PC it did *not* install.
You can check by typing About your PC in the search box on your taskbar to confirm that your device is using the expected OS build.
See: https://support.microsoft.com/en-gb/help/4093112/windows-10-update-kb4093112