Windows Update Error Code 646: What’s It & How To Fix

Windows Update Error Code 646 Occurs on Windows 7 and Windows 8.1

Windows Update is a convenient feature used frequently by users to install updates not only from Microsoft, but also from third-party providers. However, they encounter a series of Windows Update error codes while updating. Windows Update Error code 646 is one of them; it occurs when users try to install updates to their Microsoft Office – the Windows Installer discovers an issue during the process. According to users’ feedback, the 646 code seems to be exclusive to Windows 7 and Windows 8.1.

When users open Windows Update and try to install update to their Microsoft Office, they see the following error (* updates failed).

Error(s) found:

Code 646 Windows Update encountered an unknown error.

You see this error, and you realize the requested updates or automatic updates have failed. You should take actions immediately to try to solve the problem yourself. In the following content, I will show you several useful methods for troubleshooting Windows error code 646.

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Run Windows Update Troubleshooter

An essential collection of automated repair strategies are included in the Windows Update troubleshooter; they can help you fix a lot of different issues. WU component will be checked for inconsistencies once the troubleshooter is initialized and a fix may be recommended if it’s viable.

1. Right click on the Start button in the lower left corner of your screen.
2. Choose Run from the WinX menu you see. (You can also open Run by pressing Windows + R.)
3. Type control into the textbox after the word Open.
4. Click OK below the box or press Enter on the keyboard to open Control Panel.
5. Choose to View by Large icons or Small icons.
6. Scroll down to find and select Troubleshooting. (You can also type troubleshoot into the search box at the top right corner to find Troubleshooting directly.)
7. Click on the System and Security link under Troubleshoot computer problems in the right pane.
8. Click on Windows Update option under Windows section.
9. Click Advanced in the Windows Update window and check Apply repairs automatically.
10. Click on the Next button and wait for the process to complete.
11. Select Apply this fix at the end and follow the instructions to complete rest steps.
12. Reboot your computer if required.

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Disable or Uninstall Firewall

Disable Windows Firewall:

1. Open Control Panel.
2. Click Windows Firewall.
3. Select Turn Windows Firewall on or off in the left sidebar.
4. Check Turn off Windows Firewall (not recommended) under both Private network settings and Public network settings.
5. Click on the OK button to confirm.

Uninstall 3rd party firewall:

1. Open Run dialog box and type appwiz.cpl.
2. Hit OK or press Enter to open Programs and Features.
3. Look for the 3rd party firewall and right click on it.
4. Choose Uninstall from the context menu.
5. Follow the instructions to complete the uninstallation process.

Force to Start Windows Update and Background Intelligent Transfer Services

1. Open Run.
2. Type services.msc.
3. Hit OK or press Enter.
4. Right click on Windows Update.
5. Choose Properties from the menu.
6. Click the arrow button after Startup type.
7. Select Automatic from the drop-down list.
8. Click Start and then Apply.
9. Repeat step 4 to step 8 to force start Background Intelligent Transfer Service.

Clear AppData Key in Registry Editor

1. Also, open Run dialog box.
2. Type regedit and click OK.
3. Copy & paste this to the address bar of Registry Editor: Computer\HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders.
4. Press Enter and look for AppData in the right pane.
5. Right click on AppData & choose Modify.
6. Check if the value data is %USERPROFILE%\AppData\Roaming or not. If not, please change it and click OK.
7. Go to Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders and repeat step 4 ~6.
8. Go to Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders and repeat step 4 ~6.
9. Restart your computer.

You can also try to install the update through Windows Update Catalog or make use of System Restore, Repair install, and Clean Install to fix Windows Update Error code 646.

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