Quote:Windows administrators who install the October 2018 rollup patch on a Windows 7 device may run into error 0x8000FFFF once again.
Microsoft explained when update error 0x8000FFFF  happens on Windows Update last month.

It boiled down to this: Microsoft released a Servicing Stack Update for the operating system back in October 2016 and made that update a requirement  for the August 2018 update for Windows 7 Service Pack 1.

Systems threw error 0x8000FFFF when administrators attempted to install the monthly update rollout in August 2018 if the Servicing Stack Update was not installed on the device.

Microsoft promised to resolve the issue by pushing the Servicing Stack Update again to Windows Update. Previously, while it was marked critical back then, it was not installed on devices serviced with security updates only.

Microsoft wanted to avoid the same scenario by adding the security tag to the reissued update so that admins would not ignore it anymore.

Full reading: https://www.ghacks.net/2018/10/11/windows-users-are-still-hit-with-error-0x8000ffff/