The only real solution that worked for me was this
My case :
- Windows Update fails (error 0x800703f1 or 0xca00a000 or similar)
- SFC /scannow throws the following error: Windows Resource Protection could not perform the requested operation.
- DISM /Online /Cleanup-Image /RestoreHealth fails at 4.5% with Error: 1009: The configuration registry database is corrupt.
- Also tried in-place upgrade which also failed
So conventional way did not help. The steps in the link above where the only way to fix