When you try to install the Microsoft .NET Framework 1.1 Service Pack 1 (SP1) Update from the Microsoft Windows Update site on a Microsoft Windows XP-based computer, you may receive the following message in the Automatic Updates dialog box:
Updates were unable to be successfully installed
The following updates were not installed: Microsoft .NET Framework 1.1 Service Pack 1
Additionally, the WindowsUpdate.log file may contain entries that resemble the following:
To resolve this issue, use the following methods. Use each method in turn. If a method does not solve the problem, go to the next method.
Method 1: Manually remove the .NET Framework, and then reinstall the .NET Framework
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
On the computer that is experiencing this issue, remove the .NET Framework by using Add or Remove Programs. To do this, follow these steps:
Click Start, click Run, type appwiz.cpl, and then click OK.
In the list of currently installed programs, click Microsoft .NET Framework 1.1, and then click Change/Remove.
Click Yes to remove the .NET Framework 1.1.
In the list of currently installed programs, click Microsoft .NET Framework 2.0, and then click Change/Remove.
Note If the .NET Framework 2.0 is not installed on the computer, skip this step, and then go to step 2.
Follow the instructions in the Microsoft .NET Framework 2.0 Setup Wizard to remove the .NET Framework 2.0 from the computer.
Click Start, click Run, type regedit, and then click OK.
Locate and then delete the following registry subkeys: