How to fix Error 646

by Tyler Gibbs | 2010-02-15

The error 646 is typically displayed when the Windows Update agent file Wups2.dll is registered incorrectly in the registry. Because the registry files that correspond to the Wups2.dll file are missing, update installations are unsuccessful. There are two methods that can be taken to resolve this issue, use method one first and if it did not resolve your issue, proceed to method two.





Method 1: Register Windows Update
  1. Click Start and then type notepad in the Start Search box.
  2. Click Notepad in the Programs list.
  3. Copy the following commands, and then paste them into the opened Notepad window:

    REGSVR32 WUPS2.DLL /S
    REGSVR32 WUPS.DLL /S
    REGSVR32 WUAUENG.DLL /S
    REGSVR32 WUAPI.DLL /S
    REGSVR32 WUCLTUX.DLL /S
    REGSVR32 WUWEBV.DLL /S
    REGSVR32 JSCRIPT.DLL /S
    REGSVR32 MSXML3.DLL /S

  4. In Notepad, on the File menu, click Save As.
  5. In the Save as type list, click All Files.
  6. In the File name box, type register.bat.
  7. Save the Register.bat file to your desktop.
  8. Right-click the Register.bat file, and then click Run as administrator. Collapse this imageExpand this image. If you are prompted for an administrator password or for a confirmation, type the password or click Continue.
  9. Try to install updates again.

Method 2: Download and Install Windows Agent
For more information about how to download and install the latest Windows Update agent, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/949104/

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