.NET Framework update installation error: "0x80070643" or "0x643"

You may also experience the following issues when you install .NET Framework updates:

• The update is not installed.
• The system keeps reminding you to install this update even though you have already installed it.
• The desktop does not appear.

If you experience one of these issues, try the following methods to resolve the issue.

Method 1: Reset Windows Update components and update your computer

To reset the Windows Update components automatically, click the Fix it button or link, and then click Run in the View Download dialog box. Then, follow the steps in the Fix it wizard.

Note This Fix it Solution has two modes: Default and Aggressive. You should run the Fix it solution in Default mode to see whether it resolves your problem with Windows Update before you run it in Aggressive mode.

Fix this problem

(http://go.microsoft.com/?linkid=9665683)

Microsoft Fix it Microsoft Fix it 50202

Note This wizard may be in English only, but the automatic fix also works for other language versions of Windows. If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD or DVD, and then run it on the computer that has the problem.

For more information about how to reset Windows Update components, see the following article:

Method 2: Manually download the update from the download link and install it in clean boot mode

We suggest that you install the updates in clean boot mode to avoid interrupting non-Microsoft programs. To enter clean boot mode on a computer, follow these steps:

1. Click the Start button, type msconfig in the Start Search box, and then press Enter. If you are running Windows 8 or Windows 8.1, type msconfig on the Start screen, and then press Enter.
2. If you are prompted for an administrator password or for confirmation, type the password or click Continue.
3. On the General tab, click Selective Startup.
4. Under Selective Startup, clear the Load Startup Items check box.
5. Click the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.
6. Click OK.
7. When you are prompted, click Restart.
8. After your computer restarts, try to update your computer again.

For more information about this method, see the following article in the Microsoft Knowledge Base: