How to detect this? Rated 3 out of 5 stars

It works, but I cannot find a way to detect if this is installed. There is no mention of .NET or CLR in the userAgent (anymore) in Firefox 35.

How do I detect the availability of the ClickOnce extension, so I can switch in javascript between mentioning the plugin and running a WebLauncher?


Works as advertised Rated 5 out of 5 stars

I needed this to use some internal software at work. Using this, together with Stylish and AutoAuth, I don't need to open anything in IE anymore. :)

Microsoft failed at this one Rated 1 out of 5 stars

Honestly, who would want an extension which you can't get rid of?! Big thanks to CanopusArchives because he(or she) really gave some useful advice on removing this garbage. Long time thinking it was adware. AND there's more.





Rated 3 out of 5 stars


Rated 1 out of 5 stars

Useless, adware

sure it's useless but required for some pages Rated 4 out of 5 stars

such as some tutorials in microsoft technet :(

Rated 1 out of 5 stars

The most useless Addon I know.

Rated 4 out of 5 stars

"You can only remove it when you do this:
In Registry Editor:
- Go to
HKEY_LOCAL_MACHINE \ SOFTWARE \ Mozilla \ Firefox \ Extensions
- Delete value {20a82645-c095-46ed-80e3-08825760534b}
In Firefox:
- Go to about:config
- enter microsoftdotnet in Filter
- Right-click general.useragent.extra.microsoftdotnet
- select Reset.
- Restart Firefox."

NOTE: In later editions of Firefox it is only the above key that needs to be deleted, there is no corresponding entry in about:config. Restarting Firefox after deleting the key will no longer display this add-on in add-ons

Rated 1 out of 5 stars


いい Rated 3 out of 5 stars

この拡張機能は、インストールされている。NET Frameworkバージョン3.5 SP1が必要で、ClickOnceをサポートするためにMicrosoftから発行され、唯一の公式拡張機能です。あなたは無料のマイクロソフトをダウンロードすることができます。NET Frameworkのアシスタント1.2.1今。

from (

Necessario ma ingombrante. Siate consapevoli. Rated 3 out of 5 stars

Necessario ma ingombrante. Siate consapevoli.

Goodware Rated 5 out of 5 stars

I'm not a Developer so I don't have a use for this add-on but that doesn't make it useless, Believe it or not there ARE people who use .application files.

P.S. don't whine; at the very least be thankful that Microsoft registered their add-on with Mozilla.

P.P.S. If you want to remove it then Reinstall it through AMO (

Help Please Rated 1 out of 5 stars

OK I need an opinion .. I want to download the newest version of Firefox but it says I will have the Microsoft .net framework assistant disabled because the one I have isn't compatible.. DO I NEED to have this update to successfully run Firefox ( I have no clue and NOT ashamed to say so ) HELP Please

Not needed for using Firefox, not harmful either

See here: to remove it. It's simply an extension for launching a specific type of .NET Framework Application called a "ClickOnce application". If you don't know what one is, you can either safely ignore it completely or follow the instructions above to uninstall.

Huh? Rated 1 out of 5 stars

Well I always do manual updates. So I hadn't updated for at least 3 weeks. Opened Firefox and it installs. Uninstalled through the add-on manager. Maybe I did download it in an update. Didn't expect a Windows update to include an add-on for Firefox.

I guess it's good for Firefox to be mainstream but it's not IE for a reason, a GOOD reason. Lets keep it that way.

Rated 5 out of 5 stars

It's not at all useless if you work with and use Visual Studio.

Much Ado About Nothing Rated 4 out of 5 stars

Seriously, all the fuss that you chicken littles are making over this little Add-on: Windows Update setting changes, patch installs, registry hacks, forum posts, whining, crying, etc.

I've said it before but I think it bears repeating.

* This Add-on helps Firefox launch applications from the browser that were deployed with Microsoft's Click-Once technology (think "kind of like Java applets"), that way you aren't "forced" to use Internet Explorer.

* This Add-on DOES NOT circumvent security

* Technically, this Add-on WAS NOT installed without permission. It was part of a Windows update which, if you received, you gave consent to.

* True, the Add-on cannot be uninstalled through the Add-ons Manager, but it CAN be disabled through it. And for the crybabies, Microsoft provides an update to remove it.

Guess what? There is another extension that was "installed without permission" (so to speak), cannot be removed through the Add-ons manager and also helps apps run from/within the browser. It's called...

Java Quick Starter

But I don't hear anybody b!tching about that one or talking smack about Sun/Oracle. If Microsoft gets your panties all twisted then STOP USING WINDOWS!

Haters gonna hate...

This user has a previous review of this add-on.

ClickOnce forever Rated 1 out of 5 stars

Not needed, big pain to get rid of.

This from Microsoft:

"A key goal of ClickOnce is to provide a trustworthy deployment model for users to be able to download and execute applications from centrally managed servers without requiring administrator privileges on the client machine"

I am the administrator (one and only user) and don't need to circumnavigate admin. privileges via 'ClickOnce'. Many here are probably in the same boat.

Microsoft deliberately built this extension as a "machine-level" application, meaning you (the user) can't uninstall it, even if your the 'administrator'.

.netsp1 supposedly addresses this problem, but I, like many commenting here can't get it update to the fix (at least through Firefox) - catch 22.

I eventually deleted the extension following the suggestion below before manually download the update from MS, so I hope this is the last word, but as a backup I'll use this update (hopefully) to finish off the beast.

As a side note, FF needs to have a better handle on its add-ons or they are going to continue to lose market share. This automatic add-on update at the start of FF needs to go and they need to have an uninstall button for all non-essential extensions. This is my second unwanted extension I couldn't uninstall through the 'add-on' panel and I'm not happy.

Rated 5 out of 5 stars

There are many websites on the internet with applications that need this to run. It's fine.

A solution to reinstallation (?) Rated 1 out of 5 stars

I hate this addon and have also been plagued by it being reinstalled by MS.
I *think* I found the solution though....

1) Start with this:
2) Use Method 2... BUT ... only do steps 1 and 2.
Yes, the Preference isn't there, but you can create a new one (right click anywhere in the preferences wiindow... and... New) and then Reset it as instructed.

The addon is gone from my addons list... and... I think MS will still see it's installed because I haven't messed with their folder.

I'll repost if it comes back.
.... Rick

I don't understand Rated 2 out of 5 stars

I don't understand what this does and why it seems to be desperately needed on my system, it updates every time I run Firefox so, any clarification would be appreciated, especially as to why it updates to version 0.0.0

Update .NET 3.5

Hi Kenpei,
The 0.0.0 version shipped as part of the per-user update (see here: ) but I'm unsure why it's happening every time you start FF. This is not the same as this copy of the extension, which is only the same in name to the original.

If you do not run ClickOnce .applications on your machine, I suggest just following the instructions you can find on the web (or on the reviews for THIS extension) to remove it... example: .