Windows Update 0X80070420 Error Repair

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Windows Update 0x80070420 error appears when you try to update Windows using the Windows Update program or Microsoft Update websites to install new patches on your computer. The error 0x8007040420 prevents the update from terminating and prevents you from using the latest version of Windows. The error is mainly caused by corruption or damage to files or settings, which means that they do not work properly in your system. You must be able to fix these errors in order to update Windows again. This tutorial is a functional solution to the problem.


To fix the Windows Update error 0x80070420, you must first check if Windows Installer 3.1 is installed on your PC or not. This error means that you cannot install Windows updates when you try to access them from the website. This happens when Windows updates stop in the middle of the installation process.

Run the troubleshooter for Windows Update.


Download the Windows Update patch, then select Open or Save in the pop-up window.

If you choose Save, when the download is complete, you must go to the folder where the troubleshooter downloads, then double-click on the last file wu.diagcab to run the troubleshooter.
Select Next and follow the steps in the wizard to find and resolve problems with Windows Update.

February 2021 Update:

We now recommend using this tool for your error. Additionally, this tool fixes common computer errors, protects you against file loss, malware, hardware failures and optimizes your PC for maximum performance. You can fix your PC problems quickly and prevent others from happening with this software:

  • Step 1 : Download PC Repair & Optimizer Tool (Windows 10, 8, 7, XP, Vista – Microsoft Gold Certified).
  • Step 2 : Click “Start Scan” to find Windows registry issues that could be causing PC problems.
  • Step 3 : Click “Repair All” to fix all issues.


Download the latest Servicing Stack Update (SSU)

Servicing Stack Update (SSU)

  1. Determine whether you are using 32-bit or 64-bit Windows:
  2. From Start, select Settings.
  3. Select System.
  4. Click on Info.
  5. Scroll to the system type.
  6. Download the latest version of SSU (KB4456655) corresponding to your Windows version from the Microsoft Update catalog.
  7. Restart your device and check for updates.

Stop the Windows Update service.

Restart the Windows Update Service

To solve this problem, you must first stop the Windows Update service (you can then restart the service). To do this, follow these steps:

Close all windows of the Windows Update or Microsoft Update browser.
Click Start, type “cmd” in the search field, right-click on the result of the command prompt, and then click Run as administrator. Enter the administrator password when prompted or confirmed.
In the Command Prompt window, type the following commands. Don’t forget to press “ENTER” after each command.

net stop wuauserv
net start wuauserv

RECOMMENDED: Click here to troubleshoot Windows errors and optimize system performance