Windows update fails with error code 0x643

We can try to repair the installation of the Windows Installer + .NET Framework

1. Download the Windows Installer package:

(Vista Only): http://www.microsoft.com/downloadS/details.aspx?familyid=5A58B56F-60B6-4412-95B9-54D056D6F9F4&displaylang=en

(Win2k3, XP): http://www.microsoft.com/DownLoads/details.aspx?familyid=889482FC-5F56-4A38-B838-DE776FD4138C&displaylang=en

2. Click START
3. Type 'cmd' (without quotes). Right click the result at the top of the START menu and select 'Run as Administrator' (Windows 2k3, XP, and below will have to click 'Run' first)
4. Type CD %windir%\system32 and press enter. This will place us inside the windows\syste32 directory
5. Type attrib -r -s -h dllcache  and press enter
6. Type ren msi.dll msi.old and press enter - this will rename the file and essentially make it a backup
7. Type ren msiexec.exe msiexec.old and press enter - this will rename the file and essentially make it a backup
8. Type ren msihnd.dll msihnd.old and press enter - this will rename the file and essentially make it a backup
9. Once these files have been renamed, just restart your computer. Once the computer has booted back into Windows, complete step 10 to finish the installer repair process
10. Locate the Windows Installer package you downloaded in step 1. Launch the install package, follow the on-screen instructions, and once finished, restart your computer
11. Once restarted, download the .NET Framework Cleanup Tool located here:

http://blogs.msdn.com/astebner/attachment/8904493.ashx

12. Download the file (location of download is not important). Once downloaded, run the utility and select to remove ALL versions of .NET Framework. Let the utility analyze the installed packages and components on the machine. Do NOT interrupt the removal process
13. After the removal process is complete, restart the computer
14. Once restarted, download .NET Framework 3.5 located here:

http://www.microsoft.com/downloads/details.aspx?FamilyId=333325FD-AE52-4E35-B531-508D977D32A6&displaylang=en

15. Once the package has been downloaded, install it, and then restart the machine

***

16. Finally , try and perform your Windows updates as previously

Thank you very much for you patience on this matter,

Let us know if this resolves your issue. If it does not, we can attempt to log the Windows Installer to come up with more plausible solutions.

Thanks!

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Ryan Thieman

Microsoft Answers Support Engineer

Visit our Microsoft Answers Feedback Forum and let us know what you think.

thanks! Dan, try to follow the Ryan Thieman's instruction above... that works for me 100%...

Hi,

Try the KB here that Pa Bear provided - if no luck use the method in the 1st response in this thread.

See if running the newly-available Patch Registration Cleanup Tool & a reboot helps at all.

Description of the Patch Registration Cleanup Tool

http://support.microsoft.com/kb/976220/ 

Good Luck

Rob - Bicycle - Mark Twain said it right.

What does works for you?

Sorry I am lost and its past midnight here...

Dan

that works! thanx!

My make of PC is an HP pavilion with a pentium 4, 3GHz.