by boco » 27.08.2019, 10:41
Did you include Service Packs? The unpatched Win 8.1 might lack the big Update3, which is actually required for any further updates.
Microsoft update catalog: http://catalog.update.microsoft.com/v7/site/
Windows Install media download: https://support.microsoft.com/en-us/help/15088/windows-create-installation-media