Windows Update error 0x80070020 appears when a file or process is locked or in use—commonly caused by active antivirus scans, disk indexing, or background apps interfering during the update, which stops patches from installing properly. To resolve it, first restart your PC to clear any locked files or stuck services. Then temporarily disable any third‑party antivirus, firewall, disk indexing, or security tools that might be monitoring files during updates. Next, stop Windows Update services: open an elevated Command Prompt and run:
net stop wuauserv
net stop bits
After this, clear the update cache by deleting all contents of
C:WindowsSoftwareDistribution and C:WindowsSystem32catroot2, then restart the services:net start bits
net start wuauserv
Finally, run Windows Update again. The patches should now install without interference. If the error persists, reboot into clean‑boot mode, re‑run Windows Update, and re‑enable your security tools afterward. For a detailed, step‑by‑step walkthrough with troubleshooting tips, check out this guide.