Windows Update Failed To Install? Fix - 0x80070643

Windows Update error 0x80070643 often means your system is stuck in a loop, failing to install the same update repeatedly after a restart. Instead of letting Windows Update retry indefinitely, you can bypass the automatic process by manually installing the specific package from Microsoft.

Why this happens

This error typically occurs when the Windows Recovery partition lacks enough free space or when there is corruption within the .NET Framework or system files. A manual install bypasses these local triggers to apply the update directly.

Steps

1. 01
   Open the Start menu, type 'Windows Update', and press Enter to open your update settings.
2. 02
   Locate the failed update in your history or dashboard and copy down the specific KB number, for example, KB5077241.
3. 03
   Navigate to the Microsoft Update Catalog at https://catalog.update.microsoft.com in your web browser.
4. 04
   Enter the KB number into the search bar and press Enter.
5. 05
   Find the result that matches your specific system version, such as Windows 10 or 11 x64, and click the 'Download' button on the right.
6. 06
   Click the link inside the pop-up window to download the .msu file to your computer.
7. 07
   Once the download finishes, double-click the .msu file to launch the standalone installer.
8. 08
   Click 'Yes' if a permission prompt appears to begin the installation, then wait 1 to 3 minutes for it to complete.
9. 09
   Restart your PC once the installer finishes, then return to Windows Update to confirm the KB number is no longer listed as failed.

Still not working?

If the update still fails after a manual install, your system might have a corrupted Windows Recovery partition or a deeper underlying file integrity issue. Check your Windows Update logs to see if a specific error code appears during the .msu installation, and consider running the System File Checker by opening Command Prompt as administrator and running sfc /scannow.

Frequently asked questions

Is it safe to download updates from the Microsoft Update Catalog?

Yes, the Microsoft Update Catalog is an official Microsoft repository. All files hosted there are digitally signed by Microsoft and are safe to install.

Will I lose my files by manually installing an update?

No, a manual update installation only applies the necessary system patches. It does not delete, modify, or move your personal documents or installed applications.