Problem: Error 8000FFFF “Windows Update encountered an unknown error” show when perform KB4457144 security updates on Windows Server 2008 R2 or Windows 7. This is a known issue, Windows 7 / Windows Server 2008 R2 may fail to install the cumulative update if you do not have KB3177467 Servicing stack critical updates for Windows 7 SP1 and Windows Server 2008 R2 SP1 September 2016 installed.
Solution: Apply KB3177467 Critical Updates
Step 1: Download and install KB3177467 Critical Updates from Microsoft Update Catalog.
Step 2: Restart computer.
Step 3: Run Windows Update again or manually download and install KB4457144 Security Updates from Microsoft Update Catalog.
Reference
Sysnative: Error Code 8000FFFF Windows Update Windows Server 2008 R2
AskWoody: Reported error 0x8000FFFF with the Win7 Monthly Rollup KB 4457144
AskWoody: Solution for the error 0x8000FFF in Windows 7
