You receive “0x80070643” or “0x643” error codes when you try to install .NET Framework updates through Windows Update or Microsoft Updates

You receive one of the following error codes when you try to install .NET Framework updates through Windows Update or Microsoft Update, or when you attempt to update malware signatures in Microsoft Security Essentials.
Or

This problem can be caused by system corruption on your computer. This occurs for various reasons, including but not limited to other applications overwriting of .NET files or corrupted hard disk sectors.

To troubleshoot this issue, you must fix MSI software update registration corruption issues or repair the .NET Framework.

To troubleshoot this problem use the steps listed in the methods below starting with Method 1.

Method 1: Fix MSI software update registration corruption issues

To fix MSI software update registration corruption issues automatically, click the Fix it button or link. Click Run in the View Download dialog box, and then follow the steps in the Fix it wizard.





Note this wizard may be in English only; however, the automatic fix also works for other language versions of Windows.

Note if you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD and then run it on the computer that has the problem.

For more information about how to fix this issue, click the following article number to view the article in the Microsoft Knowledge Base: Visit Windows Update, and attempt to install updates again, or update Microsoft Security Essentails. If the issue is not resolved, go to method 2.

Method 2: Repair the .NET Framework

Repair the version of the .Net Framework that you fail to install updates.

.NET Framework 4

Windows Vista and Windows 7 users follow these steps to repair the .NET Framework 4 installation:

1. Close any currently running applications.
2. Click Start, and type Uninstall in the Search box and then click Uninstall a program.
3. Double-click Microsoft .NET Framework 4 Client Profile to launch .NET Framework 4 Client Profile Maintenance dialog.
4. Select Repair .NET Framework 4 Client Profile to its original state and click Next.
5. Allow the repair to complete and then click Finish.
6. Click Restart Now to restart your computer.
7. Visit Windows Update, and attempt to install updates again.

Windows XP users follow these steps to repair the .NET Framework 4 installation:

1. Close any currently running applications.
2. Click Start, click Control Panel and then click Add or Remove Programs.
3. Click Microsoft .NET Framework 4 Client Profile from the list of installed programs and click Change/Remove.
4. Select Repair .NET Framework 4 Client Profile to its original state and click Next.
5. Allow the repair to complete and then click Finish.
6. Click Restart Now to restart your computer.
7. Visit Windows Update, and attempt to install updates again.

.NET Framework 1.0, 1.1, 2.0, 3.0, 3.5

To repair the .NET Framework 1.0, 1.1, 2.0, 3.0, 3.5, you must uninstall multiple versions of the .NET Framework by using the .NET Framework Cleanup Tool, and then reinstall the components.

To do this, follow these steps:

1. Visit the following blog post:
   .NET Framework Cleanup Tool User's Guide (http://blogs.msdn.com/b/astebner/archive/2008/08/28/8904493.aspx)
2. Download dotnetfx_cleanup_tool.zip from the following link on the site:
   http://blogs.msdn.com/cfs-file.ashx/__key/CommunityServer-Components-PostAttachments/00-08-90-44-93/dotnetfx_5F00_cleanup_5F00_tool.zip (http://blogs.msdn.com/cfs-file.ashx/__key/CommunityServer-Components-PostAttachments/00-08-90-44-93/dotnetfx_5F00_cleanup_5F00_tool.zip)
3. Extract dotnetfx_cleanup_tool.zip.
4. Among the files that you extracted, double-click cleanup_tool.exe to run.
   You may be prompted for an administrator password or for a confirmation. Type the password, or click Continue.
5. When the “Do you want to run the .NET Framework Setup Cleanup Utility?” message is displayed, click Yes.
   Note this tool may be in English only; however, it also works for other language versions of Windows.
6. When you are prompted to accept the license agreement, click Yes.
7. .Net Framework Cleanup Tool starts.
8. In Product to cleanup, from the drop-down list box select a .Net Framework version that you want to remove, and then click Cleanup Now.
   Note The cleanup tool does not let you remove the .NET Framework 2.0 in Windows Vista or later versions because the .NET Framework is installed as an operating system component.
9. After the .Net Framework is removed, restart the computer.
10. Download and install the following components:
    .NET Framework 3.5 SP1 (this will also install .Net Framework 2.0 SP2 and .Net Framework 3.0 SP2)
    Microsoft .NET Framework 3.5 Service Pack 1 (http://www.microsoft.com/downloads/details.aspx?familyid=AB99342F-5D1A-413D-8319-81DA479AB0D7)
    .Net Framework 1.1 SP1:
    Microsoft .NET Framework 1.1 Service Pack 1 (http://www.microsoft.com/downloads/details.aspx?familyid=A8F5654F-088E-40B2-BBDB-A83353618B38)
    .Net Framework 1.1:
    Microsoft .NET Framework Version 1.1 Redistributable Package (http://www.microsoft.com/downloads/details.aspx?FamilyID=262d25e3-f589-4842-8157-034d1e7cf3a3)
11. Restart the computer.
12. Visit Windows Update, and then check for and install updates.

Known Issues

You may also encounter the following issues when you try to install this update:

• The update installation fails.
• The system keeps reminding you to install this update although you already installed it.
• The desktop does not load.

If you encounter one of the issues mentioned above, you may try the following methods.

Click here to view or hide detailed information

If you are not installing .NET Framework Updates when you receive error code 0x80070643 or 0x643, it may be necessary to capture additional logging information to be able to troubleshoot your issue.
These logs can be reviewed by support professionals or IT professionals to help determine the issue.

To do this, click to follow the steps listed in the following KB article on the Microsoft website Microsoft Knowledge Base:

If this article does not answer your question, click this button to pose your question to other community members at Microsoft Answers: