How to Fix Windows Update Error Code 646

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Windows update error code 646 is generated by Microsoft Office, which is one of the most widely used and popular office productivity suites today. The standard package includes a Word processor, spreadsheet, presentation and a mail client. These modules can be purchased individually for standalone desktop systems or can be purchased as an entire suite for office use.

What is the error “Windows update error code 646″?

This error is basically generated by the Windows Installer when it is trying to update components of Microsoft Office. This is still considered an error of Windows update because it is this service that gives the error and not the MS office component.

Errors that appears on the screen

Error 1 –
“Error 1606 Could not access network location %APPDATA%”

Error 2 –

Software that display Windows update error code 646
•    All versions of Microsoft Office

How to fix Windows update error code 646?

This error occurs when a firewall is enabled on your computer. As it is basically a windows installer error, it is always better to delete the AppData keys in the registry to resolve this error.

Here are the steps –

Step 1 – Disable the Firewall- If you have a firewall installed, disable it for some time and download the required windows and Microsoft Office updates. Sometimes, the firewall blocks important updates for Windows. If this doesn’t solve the problem try the next step.

Step 2 – Delete the AppData Key from the registry

Warning – The Registry is an important Windows component. Remember to make a backup before proceeding to the steps listed below.

Delete the AppData Key in Windows 7

  1. Click Start and in the search box type regedit.
  2. Right-click regedit in the Programs list and select Run as administrator.
  3. Enter the password for your user, if prompted.
  4. In the Registry Editor window that opens, locate the key –
    HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
  5. In the right pane locate AppData and check if its value is  %USERPROFILE%\AppData\Roaming.
  6. If the value is different,
    Right-click on AppData and then select Modify.
  7. Add %USERPROFILE%\AppData\Roaming in the value data box and click OK.
  8. Now go to –
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders and HKEY_LOCAL_MACHINE \Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders.
  9. Repeat steps 5 and 6 for the AppData key here.
  10. Close Registry Editor and restart your system.

On Windows XP, perform the following steps to resolve Windows update errors 646 –

  1. Click Start, select Run, type regedit and press Enter.
    Registry Editor window will display.
  2. Browse to HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
  3. Locate AppData on the right side of the registry window and check if its value is %USERPROFILE%\Application Data.
  4. If the value is incorrect, right-click AppData, select Modify and then enter the correct value.
  5. Now browse to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders and change the value of the AppData as mentioned in step 3 and 4.

After performing the above steps, you may run the sfc/scannow at Command Prompt to check and replace any modified system files and prevent the problem from recurring.