Neil Turner's Blog

Blogging about technology and randomness since 2002

Uninstalling Firefox Extensions

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This is an example of a blog post that I probably shouldn’t have to write. As the title suggests, it’s to do with uninstalling Firefox extensions, which should be as simple as opening the Addons Manager and selecting ‘Remove’, and then restarting Firefox. Unfortunately, it isn’t always that simple: some extensions – and it’s generally those installed by third-party applications – can’t be removed this way; the ‘Remove’ button isn’t there. These addons can be disabled, but they’ll still show in the list.

The main culprits are the Java Console, Java Quick Start and Microsoft .NET Framework Assistant, which are installed as part of Oracle’s Java Runtime Environment and Microsoft’s .Net Framework respectively, but there are others as well. This is because Firefox allows addons to be installed in several different folders:

  1. In the Firefox user profile folder – this is the preferred location and addons installed here should be uninstallable (if that is a word) via the normal way – i.e. through the Addons Manager.
  2. In the Firefox application folder – extensions installed here are available to all users of a machine, not just the user who installed it. This is where the Java Console gets installed. On Windows, this is usually C:\Program Files\Mozilla Firefox\Extensions .
  3. Any random folder, linked in the Windows Registry – on Windows, extensions can add entries to the Windows Registry to have Firefox load them, and these can be in any folder on the user’s computer. The Java Quick Starter and .Net Framework Assistant are installed in this way

So how do you get rid of those installed using the other two methods? If it’s in the Firefox application folder, open C:\Program Files\Mozilla Firefox\Extensions and then look at each of the sub-folders. The folder called {972ce4c6-7e08-4474-a285-3208198ce6fd} should be left well alone, as this is the default Firefox theme, but the others you’ll need to look at in turn to see what they are and if they’re worth keeping. Popping the folder names into Google may help.

If after clearing this folder out, you still have unwanted and non-uninstallable (another made up word?) extensions, you’ll need to look into editing the Windows Registry. I won’t tell you how to access it, because if you don’t know then you shouldn’t be meddling with the Registry – changing or deleting the wrong thing can completely break Windows. Extensions can be listed in one of two places:


Go into these keys and have a look at the values. You’re probably best just deleting the values, rather than trying to delete the folders that these extensions come from. Restart Firefox, and they should now be gone.

To be honest, doing this is overkill; if an extension is disabled then other than clogging your extension list it’s not doing any harm. And Firefox 8.0, released this week, will disable any addons that you haven’t installed yourself by default when you run it for the first time. But if you must remove that one niggling extension and Firefox won’t let you do it the easy way, now you know what to do.

This entry was written with the help of the Uninstalling add-ons and Installing Extensions articles in the MozillaZine Knowledge Base.

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