I cannot install update "Microsoft .NET Framework 3.5 Service Pack 1 and .NET Framework 3.5 Family Update (KB951847) x64". Windows Update encounters a reportedly unknown error code 643 and the update fails. How can I fix this? PS: I am running Microsoft Windows Vista 64-bit (ENU) with Service Pack 2 (SP2) on an HP Pavilion dv5-1199eg Entertainment Notebook PC.

ok how do you do this for windows xp pro 64bit ? {update, jamesa1946 solution worked like a charm! i noticed the download link for 3.5 was a diff size also,that might of did it. but it worked and this pain in the neck is finally gone lol good luck to all!}

Oh my gosh, ooniemcgoonie , You ARE a genius! I have tried for literally months to solve this problem. First I spent an hour on the phone with a Microsoft (not very smart) tech and he could NOT help me at all. Then I emailed the techs at Microsoft and they sent me detailed info of what I needed to do. The info they sent was SO wrong! They did not even have the correct links for me to use! Any way I just wanted to thank you for solving this mysterious problem that seems to be plaguing a lot of people. Too bad your info is not on the other boards. I also am using Vista Home Premium 64 bit! Thanks to you I can now install my new Corel PSP X3 software! Shylo

Oh dear, I'm in a right old mess now: I followed all of step one, then my computer told me to restart to make the changes take effect. Now every time I re-start it I get Windows Installer starting up, trying to install PhotoGallery, but it can't complete as there are multiple error messages (2908), followed by Error something else long and complicated. So when I tried to re-install Microsoft.net 2.0 (the first one in step 2), it wouldn't install as the computer was still trying to install PhotoGallery. I can't even turn the computer off without crashing it at the on/off button, as Windows installer keeps trying again to install PhotoGallery. I just wish I'd left well alone: think I'll be looking at a complete re-install of Windows now! By the way, I see I've also got Microsoft.net 1.1 and 3.0 on my computer: should I not have removed am re-installed them all? Following up on 25/01/10: I managed to get rid of the offending PhotoGallery that kept trying to re-install itself, by using Windows Installer Clean-up, then followed through Zhao's suggested steps: all went well with re-installing Ms.Net SP 2 and associated updates. When I downloaded the first of the downloads for 3.5, it only showed a 99% download, so refused to install: here's the error message, which looks something like one posted above by DavSamuels. [09/26/09,22:57:17] Microsoft .NET Framework 2.0a: [2] Error: Installation failed for component Microsoft .NET Framework 2.0a. MSI returned error code 1603 [10/12/09,10:52:17] Microsoft .NET Framework 2.0a: [2] Error: Installation failed for component Microsoft .NET Framework 2.0a. MSI returned error code 1603 [12/31/09,17:08:12] Microsoft .NET Framework 2.0a: [2] Error: Installation failed for component Microsoft .NET Framework 2.0a. MSI returned error code 1603 [01/01/10,21:53:58] Microsoft .NET Framework 2.0a: [2] Error: Installation failed for component Microsoft .NET Framework 2.0a. MSI returned error code 1603 [01/25/10,12:18:16] Microsoft .NET Framework 3.0 SP2 x86: [2] Error: Installation failed for component Microsoft .NET Framework 3.0 SP2 x86. MSI returned error code 1603 [01/25/10,12:18:48] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0 SP2 x86 is not installed. Anyway, can someone tell me what all this Microsoft.Net does: the explanation given my Microsoft is all gobble-de-gook to me! Do I need it? What will happen if I don't have it? Etc, Etc Windows XP on a Dell. Trish S

After many attempts to find a solution to update .NET Framework 3.5, your solution worked. Many thanks. I running Vista Home Premium 64 bit.

Error Code: 643 (Can't install KB951847)

Answer accepted by question author

Anonymous

I received the following Microsoft fix today.

I have been receiving instructions from a Microsoft Tech since last Thursday.

Some of you are likely seeing a Windows Update icon in your system tray right now. DONOT download those updates until you have done the following listed below.

Be sure to follow the instructions carefully. This fix repaired my problem and I was able to download all the new .net framework security updates successfully.

This applies to those using Windows XP and it repaired the problem:

I understand that the following 2 updates still cannot be installed. The error code 0x645 is received.

Microsoft .NET Framework 2.0 Service Pack 2 Security Update for Windows 2000, Windows Server 2003, and

Windows XP (KB974417)

Microsoft .NET Framework 3.5 Service Pack 1 and .NET Framework 3.5 Family Update for .NET versions 2.0 through 3.5 (KB951847) x86

In order to narrow down the cause of this issue and resolve it, please refer to the following steps.

Step 1: Use .Net Framework CleanUp Utility

============================================

Please download the .NET Framework Cleanup Tool from the following link:

http://windowsuu.com/tools/dotnetfx\_cleanup\_tool.zip

Please Note: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

Unzip the file and then close all the open windows.
Double click Cleanup_tool.exe to run it, and then select the .Net Framework 2.0 in the list box. Click “OK”, click “Yes”, and click “Cleanup Now” to remove it completely. After that, please also remove the .NET 3.5.

Step 2: Reinstall .NET Framework Version 2.0, 3.5 and their updates

==================================================

Please download and install the following updates in order.

Microsoft .NET Framework Version 2.0 Redistributable Package (x86)

http://download.microsoft.com/download/5/6/7/567758a3-759e-473e-bf8f-52154438565a/dotnetfx.exe

Microsoft .NET Framework 2.0 Service Pack 2

http://download.microsoft.com/download/c/6/e/c6e88215-0178-4c6c-b5f3-158ff77b1f38/NetFx20SP2\_x86.exe

Microsoft .NET Framework 2.0 Service Pack 2 Security Update for Windows 2000, Windows Server 2003, and Windows XP (KB974417)

http://download.microsoft.com/download/A/0/1/A01064A3-CAB0-4851-9C54-56A980FF00EB/NDP20SP2-KB974417-x86.exe

After that, please restart the computer and then install Microsoft .NET Framework 3.5 and its update.

Microsoft .NET Framework 3.5 and .NET Framework 3.5 Service Pack 1

http://download.microsoft.com/download/2/0/E/20E90413-712F-438C-988E-FDAA79A8AC3D/dotnetfx35.exe

Microsoft .NET Framework 3.5 Family Update

http://download.microsoft.com/download/C/6/A/C6ADC586-2518-404B-8973-E1E22C556AF4/NDP35SP1-KB958484-x86.exe

Note: When the file download window appears, please click "Save", and follow the directions to save it on the Desktop. After downloading the setup file on your Desktop, double-click to manually install it.

However, if any error is encountered when installing, please capture a screenshot of the error message:

How to capture a Screenshot:

======================

When the error appears, please press the "Print Screen" key (PrtScn) on your keyboard.
Click "Start", click "Run", type MSPAINT, and click "OK".
In Paint, click "Paste" under the "Edit" Menu, click "Save" under the "File" menu, type a file name for the screenshot, choose JPEG as "Save as type", click "Desktop" on the left pane, and click "Save".
Please find the screenshot on the Desktop and send it as an attachment to: *** Email address is removed for privacy ***.

Please try my suggestions and let me know the results at your earliest convenience. If you have any other questions, please do not hesitate to let me know.

I look forward to your response.

Best Regards,

William Zhao

*** Email address is removed for privacy ***

Microsoft Windows Update Support Professional

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Error Code: 643 (Can't install KB951847)

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