How to remove the .NET Framework Assistant for Firefox

In the .NET Framework 3.5 SP1, the .NET Framework Assistant enables Firefox to use the ClickOnce technology that is included in the .NET Framework. The .NET Framework Assistant is added at the computer level so that its functionality can be used by all users at the computer level instead of at the user level. As a result, the Uninstall button is unavailable in the Firefox Add-ons menu because standard users are not permitted to uninstall machine-level components.

To resolve this issue, use one of the following methods:

Method 1: Download the Update to .NET Framework 3.5 SP1 for the .NET Framework Assistant 1.0 for Firefox

This update installs the .NET Framework Assistant on a per-user basis. As a result, the Uninstall button will be functional in the Firefox Add-ons menu.

Note This update is included in Windows 7 and in the .NET Framework 4.0.

To download the Update to .NET Framework 3.5 SP1 for the .NET Framework Assistant 1.0 for Firefox, visit the following Microsoft Web site:

Method 2: Remove the .NET Framework Assistant for Firefox

To remove the .NET Framework Assistant for Firefox from your computer, follow these steps:

1. Delete the registry key for the extension. To do this, use one of the following methods.
   • Use Registry Editor:
     1. Log on with an account that has Administrator permissions.
     2. Click Start, click Run, type regedit, and then press ENTER.
     3. Locate and then click the following registry subkey.
        
        For x86-based computers:
        HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Firefox\Extensions
        For x64-based computers:
        HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mozilla\Firefox\Extensions
     4. Delete the {20a82645-c095-46ed-80e3-08825760534b} subkey.
   • Use a command prompt:
     1. Log on with an account that has Administrator permissions.
     2. Click Start, click Run, type cmd, and then press ENTER.
     3. At the command prompt, type the appropriate command, and then press ENTER.
        
        For x86-based computers:
        reg DELETE "HKLM\SOFTWARE\Mozilla\Firefox\Extensions" /v "{20a82645-c095-46ed-80e3-08825760534b}" /f
        For x64-based computers:
        reg DELETE "HKLM\SOFTWARE\Wow6432Node\Mozilla\Firefox\Extensions" /v "{20a82645-c095-46ed-80e3-08825760534b}" /f
2. In the Firefox user agent, reset the changes that you made in step 1. To do this, follow these steps:
   1. Start Firefox, type about:configin the Firefox address bar.
   2. Scroll down or use Filter to find the following preference item:
      general.useragent.extra.microsoftdotnet
   3. Right-click this item, and then click Reset.
   4. Restart Firefox
3. Remove the .NET Framework extension files. To do this, follow these steps:
   1. Log on with an account that has Administrator permissions.
   2. Click Start, click Run, type explorer, and then press ENTER.
   3. Open the following folder:
      %SYSTEMDRIVE%\Windows\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\DotNetAssistantExtension\
   4. Delete the DotNetAssistantExtension folder and all its contents