Resetting Firefox, How To Start Fresh With Firefox 4

Martin Brinkmann
Mar 22, 2011
Updated • Aug 21, 2013

Firefox 4 has finally been released. I do not really want to rehash all that's been said in the past twelve months or so ever since the first beta releases appeared on the Mozilla servers. Only that much: Firefox 4 is faster and really not that much different from Firefox 3.6.

Here are a few overview guides that you may want to read if you have to read up on the release, everyone else may skip ahead.

Resetting Firefox?

The basic idea behind resetting the browser is to get rid of all the "garbage" that has been accumulated ever since the browser, or the profile that is currently used, was installed for the first time. This includes leftover files, first and third party settings that have been changed or removed, extension leftovers and bloated database files. A fresh start may improve the performance and reliability of the browser. It highly depends on past usage though.

There are actually only two sets of data that I'd like to move over to the new version: Bookmarks and Extensions. Some users may have other things that they would like to keep, for instance passwords if they are using the built-in password manager to store passwords in the browser.


I like to be on the safe side of things, which is why I recommend to create a full backup of the existing Firefox profile. This backup acts as a last resort to restore the profile and data, but also as an option to restore select information from the old profile.

I recommend Mozbackup for the job, but you are free to use other means like copying the profile manually or using extensions such as FeBe instead. What I like about Mozbackup is that it takes less than a minute to create a full backup of the Firefox profile folder, and that it offers restoration options.

I suggest you take a look at my how to backup Firefox with Mozbackup guide linked above to create the backup. The basic steps are as following:

  • Download the beta version of MozBackup from the developer website. Why the beta? Because it has better Firefox 4 support.
  • Run the tool, select backup and your version of Firefox. You need to select the Firefox profile that you want to backup. If you are not sure backup all of them one after the other. Make sure you close the Firefox web browser before proceeding.
  • I recommend to backup everything to be on the safe side, but that is up to you

And that's it, you have successfully created a backup of your Firefox profile. An alternative is to configure a Firefox Sync account which automatically backs up bookmarks, passwords and settings on Mozilla servers. It would then be possible to restore those settings once Firefox 4 has been installed. Keep in mind that Firefox Sync is not backing up extensions.

Now you need to download the latest version of Firefox from the Mozilla website. This is important as we need to uninstall previous versions of the browser (skip ahead to creating a new profile if you feel less adventurous.

Uninstalling Firefox

Now it is time to completely uninstall Firefox on the system. Make sure you delete the full profile folder as well. If you have troubles locating the profile folder consult the following Mozilla Support page. You can use a program like Revo Uninstaller to catch all leftovers and Registry keys that may still be on the system after using the standard Firefox uninstaller.

Installing Firefox 4

Install Firefox 4 using the recommended settings. The browser is installed without extensions, customizations, bookmarks and everything else that you may hold dear.

firefox 4 installation

The first thing that you may want to do is to restore data that you have backed up. If you use Mozbackup it is a matter of selecting restore from the program options and then the components that you want to restore to Firefox 4.

firefox restore

It is obviously up to you what you want to restore, but I suggest to restore at least the bookmarks and extensions. Keep in mind that all extensions will start with no customization if you only restore. This means that you will spend some time configuring the extensions again. I had to enter the Last Pass master password and force compatibility checks in Firefox 4 to get an incompatible add-on working.

The Firefox interface will also be reset, which means that you may have to customize it as well. I for instance enabled the add-on bar again, got rid of the Firefox button and moved the NoScript icon to the add-on bar. Some settings, like getting rid of the new tab button can only be changed in the advanced configuration. This may take additional time if you are unfamiliar with the parameter names.

The customizations took less than five minutes to complete on my system, the time may differ depending on your experience with the browser and the number of extensions installed.

Switching to a new profile

Starting fresh may sound like a daunting task.Users who do not want to uninstall Firefox can instead create a new profile using the Firefox profile manager which acts as an independent copy as well.


A fresh start can remove old settings and data that would otherwise still be carried around. I for one have resolved my Google sign out issues with the fresh install. I also managed to reduce the profile folder by more than five Megabytes. I cannot really say for sure but the browser feels a tad more responsive as well.

Have you installed Firefox 4 yet?

Update: MozBackup Final has been released.

Update 2: Mozilla has implemented native reset functionality in Firefox.


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  1. dwarf_tossr said on March 23, 2011 at 3:02 am

    I noticed Anycolor and Element Properties extensions aren’t working with this. With any luck they get updated to work.

    Other than that, didn’t have to make too many adjustments and everything appears to be working alright. That and my Firefox doesn’t have a Firefox button and looks pretty much like it did on 3.6.15, which is great because I’m not digging the chrome look-alike treatment. So it is possible that upgrading won’t be too painful for those who are loathe to do so from 3.6.15.

    It worked best for me to make a backup of 3.6.15 profile with Mozbackup and then completely uninstall Firefox (as well as it’s folder) and then Install Firefox 4 and restore profile. The first time restoring extensions specifically made FF4 crash on start, but later on I restored everything including extensions with mozbackup and it just worked. Weird but I’ll take it.

    Other than having to use a theme rather than Anycolor (really hope it gets updated) and not having a Properties right-click item, everything is going well.

  2. MartinDK said on March 22, 2011 at 10:46 pm

    I just reformatted my laptop, and this turned out to also work quite well in order to get a fresh start with Firefox 4 ;-P

    I installed it earlier today, having not tried out the betas and RCs.
    The tabs on top are nice, but I instanty ditched the Add-on Bar and moved the icons for the installed extensions (Noscript & Adblock in my case) up to the left of the bookmarks bar (which I had, on the other hand, instantly enabled).

    It seems okay, but I’m still not sure I’ll go back to Firefox now that I have finally managed to get Chrome running the way I want . Except of course from the fact that Chrome sucks at handling bookmarks compared to it’s foxy competitor (sidebar and stay-open menu extensions for easy access to multiple bookmarks).

    But I have one major problem with FF: The orange Firefox Button at the top left corner is entirely obscured by Mediamonkey, which I have nestled up there in an always on top miniplayer mode, and I can’t figure out how to relocate the firefox button (so any hints are appreciated :-D).

    And btw., this comment was written in Chrome…

    1. Martin Brinkmann said on March 23, 2011 at 12:05 am

      Martin try the movable Firefox button add-on:

      1. MartinDK said on March 24, 2011 at 12:42 am

        Yay! That add-on worked wonders! Thank you :)

  3. Robert Palmar said on March 22, 2011 at 8:35 pm

    Great advice and instruction, Martin.
    Interesting too that this solved
    your sign-in problem.

    As usual I will have to wait a bit as
    several key extensions are yet to be
    updated though I will force them if they
    are not updated in too timely a fashion.

    I will play around with a portable version
    and copy over my local version profile folder
    to see what I may be up against on upgrading.

    1. Martin Brinkmann said on March 23, 2011 at 12:03 am

      I’m pretty happy that it resolved the issue. I think that particular Firefox profile was with me from Firefox 2 on. It was time for a clean cut. Many developers have waited for a final release to begin updating their extensions.

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