Windows Update error 0x80070020 usually occurs when another program is using essential update files, preventing the update process. To resolve this, start by closing all applications and temporarily disabling third‑party antivirus or security tools that might be locking those files. Next, restart your PC in a clean boot state to eliminate conflicts from background services. Once in clean boot, run the Windows Update Troubleshooter from Settings → Update & Security → Troubleshoot to automatically detect and fix problems. If issues persist, reset Windows Update components by stopping services (wuauserv, bits, cryptsvc), renaming the SoftwareDistribution and Catroot2 folders, then restarting the services. Finally, run
sfc /scannow in an elevated Command Prompt to repair any damaged system files. After completing these steps, reboot and check for updates again. For a detailed step‑by‑step guide, visit this comprehensive walkthrough.