Brian Ladd’s Blog – Notes on Life

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Uninstalling the Clickonce Support for Firefox

Uninstalling the Clickonce Support for Firefox

A couple of years ago we heard clear feedback from folks that they wanted to enable a very clean experience with launching a ClickOnce app from FireFox.  James Dobson published FFClickOnce and got very good reviews, but we had many customers that wanted ClickOnce support for Firefox built into the framework… so in .NET Framework 3.5 SP1 we added ClickOnce support for Firefox!     This made ClickOnce apps much more accessible to a wide range of customers.

We added this support at the machine level in order to enable the feature for all users on the machine.  Seems reasonable right?  Well, turns out that enabling this functionality at the machine level, rather than at the user level means that the “Uninstall” button is grayed out in the Firefox Add-ons menu because standard users are not permitted to uninstall machine-level components.

Clearly this is a bit frustrating for some users that wanted an easy way to uninstall the Clickonce Support for Firefox.  But good news!  We have a fix in place (enabling each user to uninstall the feature for themselves) and our testing team is making sure that is rock-solid now.. I expect that to be out in the next few weeks.   I’ll be sure to post more information on that when I have it.

Update (5/2009):  We just release an update to .NET Framework 3.5 SP1 that makes the firefox plug in a per-user component.  This makes uninstall a LOT cleaner.. none of the steps below are required once this update is installed.

Update to .NET Framework 3.5 SP1 for the .NET Framework Assistant 1.0 for Firefox

In .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 machine-level to enable its functionality for all users on the machine. As a result, the Uninstall button is shown as unavailable in the Firefox Add-ons list because standard users are not permitted to uninstall machine-level components. In this update for .NET Framework 3.5 SP1 and in Windows 7, the .NET Framework Assistant will be installed on a per-user basis. As a result, the Uninstall button will be functional in the Firefox Add-ons list. This update will also make this version of the .NET Framework Assistant for Firefox compatible with future versions of the Firefox browser. Updates to the .NET Framework Assistant may include updates to the Windows Presentation Foundation Plug-in for Firefox causing it to be enabled upon its initial update.


In the meantime, if you want to disable the Clickonce Support for Firefox here are the steps directly from the dev in charge..

Stop-gap Solution To uninstall the ClickOnce support for Firefox from your machine

1) Delete the registry key for the extension

i.                     From an account with Administrator permissions, go to the Start Menu, and choose ‘Run…’ or go to the Start Search box on Windows Vista

ii.                   Type in ‘regedit’ and hit Enter or click ‘OK’ to open Registry Editor

iii.                  For x86 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Mozilla > Firefox > Extensions

For x64 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Wow6432Node > Mozilla > Firefox > Extensions

iv.                 Delete key name ‘{20a82645-c095-46ed-80e3-08825760534b}’

OR alternatively

i.                     Open a command prompt window (must be ‘run as Administrator’ on Vista and later)

ii.                   Copy and paste the appropriate command below and hit ‘Enter’

For x86 machines:
reg DELETE “HKLM\SOFTWARE\Mozilla\Firefox\Extensions” /v “{20a82645-c095-46ed-80e3-08825760534b}” /f

For x64 machines:
reg DELETE “HKLM\SOFTWARE\Wow6432Node\Mozilla\Firefox\Extensions” /v “{20a82645-c095-46ed-80e3-08825760534b}” /f

2) Reset the changes made to the Firefox user agent

i. Launch Firefox, go to the Firefox address bar and type in ‘about:config’

ii. Scroll down or use ‘Filter’ to find Preference name ‘general.useragent.extra.microsoftdotnet’

iii. Right-click on the item and select ‘reset’

iv. Restart Firefox

3) Remove the .NET Framework extension files

i. Go to the Start Menu, and choose ‘Run…’ or go to the Start Search box on Windows Vista

ii. Type in ‘explorer’ and hit Enter or click ‘OK’

ii. Go to ‘%SYSTEMDRIVE%\Windows\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\DotNetAssistantExtension\’

iii. Delete the ‘DotNetAssistantExtension’ folder and all its contents

Published 27 February 09 12:00 by BradA

# Silvr said on April 1, 2009 4:18 AM:
According to (

“This update adds to Firefox one of the most dangerous vulnerabilities present in all versions of Internet Explorer: the ability for websites to easily and quietly install software on your PC.”

Question is :

Is the above statement true. Is Brad Adams or anyone from Microsoft able to disprove it.

I respect this site since it gave me a lot of help for a lot of stuff microsoft had long-since discontinued support for, and it has provided me great troubleshooting advice.

I agree with other comments that this  secret install borders on the level of malware.(Sony anyone?)

It was stupid on Microsofts part for the following reasons :

1. Risking flak from security community and firefox community(if this indeed creates vulnerabilities in firefox)

2. Add the fact this was install without any user notification or consent. All my other plugins and extensions were installed with permission from me.

3. Risk antitrust allegations for using microsoft update to promote microsoft products over other(java).


June 1, 2009 - Posted by | General Computer Tech, Security, Windows / Microsoft

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