Errors Found Code 0x643 Windows Update Encountered an Unexpected Error

Try to download the standalone version of the update and save it to the desktop and try to install the install the same after putting the computer in a clean boot state.

Windows Update error code “0x643” and Windows Installer error code “1603” are generic error codes. Typically, these error codes mean that the update was not installed. These errors codes are usually caused by a corruption in the . NET Framework installation or by an inconsistency on the MSI database state.

Windows update fails with error code 0x643

Error : Windows update fails with error code 0x643

I have downloaded the recent Microsoft updates and all but one installed successfully. The failing update was: Microsoft .NET Framework 1.1 Service Pack 1 Security Update for Windows 2000, Windows XP, Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2 (KB953297); with an error code of 0x643.

We tried several times to install it and it keeps failing. It was originally the 3rd update in the list to install. After failing the first time, it was the only one we were trying to install. We tried it after the restart required for the other updates.

Solution

Try to download the standalone version of the update and save it to the desktop and try to install the install the same after putting the computer in a clean boot state.

To perform a clean boot on a computer that is running Windows Vista:

1. Click Start, type msconfig in the Start Search box, and then press ENTER.

If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.

2. On the General tab, click Selective Startup.

3. Under Selective Startup, click to clear the Load Startup Items check box.

4. Click the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.

5. Click OK.

6. When you are prompted, click Restart.

7. After the computer starts, try to install the updates.

If your issue is resolved after performing Clean Boot and then installing the update, then follow the steps on how return your computer to a Normal startup mode by following the steps under “Reset the computer to start as usual”

You may also try to restart the computer in safe mode and try to install the standalone version of update KB929729. To start the computer in safe mode restart the computer and keep tapping F8 key. Once you see the option safe mode select it and press enter.

If the issue persists, let us know if you are able to install other updates apart from Microsoft .NET Framework, Version 1.1 Service Pack 1 (KB929729).  Also let us know the exact error message you receive when the installation fails.