Windows Update error 80070663 often appears when your PC fails to apply an update or patch—typically due to installation corruption, conflicts with existing updates, or issues in the Windows component store. This stops critical updates, potentially exposing your system to security risks. To resolve this, begin by running the Windows Update Troubleshooter (Settings → Update & Security → Troubleshoot → Additional troubleshooters → Windows Update) to automatically detect and repair common update issues. Next, clear the update cache: stop the Windows Update, Background Intelligent Transfer Service (BITS), and Cryptographic Services, delete all files in
C:WindowsSoftwareDistribution and C:WindowsSystem32catroot2, then restart those services to reset the update environment. After that, open an elevated Command Prompt and run sfc /scannow to repair system files followed by DISM /Online /Cleanup-Image /RestoreHealth to restore the Windows component store. Once complete, reboot your PC and re-run Windows Update. For a full, step‑by‑step walkthrough with additional recovery options, check out this detailed guide.