0x8000FFFF

Windows Update error 0x8000FFFF

Additional symptoms:

• sfc /scannow stuck at 7% and cannot complete.
• mmc.exe - app locked
• Able to run mmc.exe from Power Shell run as Administrator

Solutions:

• bitsadmin.exe /reset /allusers
• chkdks /r
• ICACLS C:\Windows\winsxs

• Servicing Stack Update
  • systeminfo - check Windows version
  • Latest SSU Updates
  • Install KB4586864

Anty malware tools:

• Farbar Recovery Scan Tool FRST