Two versions of Firefox on new laptop, how to remove one?

RandySea · Aug 11, 2026

After moving to a new Windows 11 laptop and copying programs from the old laptop with PCmover, I seem to have two versions of Firefox that look different. If I start Firefox from the Start, Programs, it looks like it did on my old laptop. It has the correct extensions and all my correct settings and bookmarks. It is Firefox Developers edition 1.45.0b9, which I’ve used for years. I want this.

But there seems to be a new, second version that looks different and does not show my extensions or bookmarks. It is Firefox Windows MSIX 1.0. This is the version that now acts as my default browser when I click on a link in an email. I don’t want this but I’m not sure how to fix this problem.

In setting up default apps in Windows, it only gives me one Firefox choice. I have no way to choose between the two shown above.

How can I fix this?

RandySea · Aug 11, 2026

I have found a folder Mozilla Firefox and a folder for Firefox Developer Edition, both in Windows, Programs.

Don Kee · Aug 11, 2026

Not to worry, If you delete both go to the Mozilla download and get the latest.

spapakons · Aug 11, 2026

No, he might lose all his data, it is too risky. Unless of course he has still the backup of the old Firefox. In that case, remove both and restore the old version from the backup.

RandySea · Aug 11, 2026

But if I delete both, won't I lose all my bookmarks, etc?

OAT · Aug 11, 2026

RandySea said:
But if I delete both, won't I lose all my bookmarks, etc?

It is Firefox Windows MSIX 1.0 you want gone then. It is the MS store version.
This one can be removed via Settings/Apps/Installed Apps/ but not via Control Panel.

spapakons · Aug 11, 2026

RandySea said:
But if I delete both, won't I lose all my bookmarks, etc?

Yes, but then you will restore the old Firefox from your backup with PCmover again. Of course make sure you can before you delete both.

Otherwise I would use a utility to backup Firefox, just in case, and then try to delete only the new version. An alternative is to copy all Mozilla folders related to the old version to another folder as backup, remove both and then copy the folders back to their original location before reinstalling Firefox. This will make the Installer think you already have Firefox and offer to upgrade. Click on Upgrade and proceed with the installation. When loading Firefox you should see all your settings, bookmarks and addons.

Edwin · Aug 11, 2026

RandySea said:
won't I lose all my bookmarks...

Export them to a file, then import them back, afterwards...

Ghot · Aug 11, 2026

RandySea said:
But if I delete both, won't I lose all my bookmarks, etc?

You can export your bookmarks to an HTML file.
Then when you do a clean install of Firefox, you can just import the bookmarks.

If I were you, I'd use REVO Uninstaller (free) to remove both copies of Firefox... and do the "Scan" for leftovers after removing each one.
Then do a clean install of Firefox and import your bookmarks.

Download Revo Uninstaller Free - Remove unwanted programs easily

Download Revo Uninstaller Free helps you to uninstall software and remove unwanted programs easily. Remove all uninstall leftovers and traces

www.revouninstaller.com

And here's some FF tweaks that may help...

Firefox... taming the beast part 2 !! - Windows 10 Help Forums

First things first... stop Firefox from automatically updating. Simply unzip and drop this "distribution" folder into... C:\\Program Files\\Mozilla Firefox After manually updating Firefox this folder will be erased, so save a copy somewher

www.tenforums.com

I'm on FF 153.0.4 at the moment, and this is what mine looks like...

cheaterslick · Aug 11, 2026

It's best just to backup your profile before you delete anything.

How to Back Up (and Restore) Mozilla Firefox Profiles

Keep your personal preferences intact!

www.howtogeek.com

Then restore it again after you do a new install.

RandySea · Aug 11, 2026

Now it just keeps getting weirder. Took two suggestions above. Exported (backed up) my bookmarks from Developer Edition just for safety. Then uninstalled the Firefox from the MS Store. That didn't harm the Firefox Developer edition, which is working fine after a reboot. Bookmarks are intact.
I then associated HTTP with Firefox and rebooted. This choice disappeared after rebooting.

After rebooting, when I clicked on a link it opened Edge. I checked the app associations. HTTPS and HTTP were reset to Edge. And Firefox was completely gone from the list of apps for associating, though it's running just fine in Start, Programs. When I start it up, it asks if I want it to be my default browser. I click on yes, but that does nothing. Default browser stays as Edge.

RandySea · Aug 11, 2026

Well, I bit the bullet and just re-installed the base version of Firefox. I imported my bookmarks from the .json file I created above. Now I have the tedious job of bringing extensions back in, and redoing scripts in NoScript. But at least it is now working as my default app.

I would still like to make the old Firefox Developer work as my default app for HTTP etc, but can't figure out how to do that.

cheaterslick · Aug 11, 2026

RandySea said:
Well, I bit the bullet and just re-installed the base version of Firefox. I imported my bookmarks from the .json file I created above. Now I have the tedious job of bringing extensions back in, and redoing scripts in NoScript. But at least it is now working as my default app.

Again, saving your profile (like I mentioned earlier), you would avoid having to do all that since not only your bookmarks but your extensions, scripts and settings would come along with it.

RandySea said:
I would still like to make the old Firefox Developer work as my default app for HTTP etc, but can't figure out how to do that.

Save your Firefox profile in a safe place. Then delete Firefox in it's entirety using Revo. That includes old folders and registry entries. Then install the following:

Firefox

Firefox Developer Edition is the blazing fast browser that offers cutting edge developer tools and latest features like CSS Grid support and framework debugging

www.firefox.com

Then import your profile using the link instruction I posted up above. Close Firefox and re-open and it should be back to where it was.

I've had to this a few times in the past so I know it works.

KevTech · Aug 11, 2026

For bookmarks you can just copy these two files from your profile then paste them back overwriting the files in your profile.

The file that holds all your bookmarks is: places.sqlite
All the icons for those bookmarks are in: favicons.sqlite

spapakons · Aug 12, 2026

But he wanted to keep everything, not only the bookmarks. I haven't worked with profiles, I don't use Firefox as my default browser, that's why I suggested to manually copy all the relevant folders before uninstalling both Firefox versions. I have done that many times. Once you copy the folders to their respective location on a new computer and then install Firefox, you have everything back.

In OP's case, once he uninstalled the undesired version of Firefox and the option to select Firefox as the default browser was gone, all he had to do was install Firefox again at the same folder as the desired version. Installer would detect the files and offer to upgrade. Proceeding with the "upgrade" would make Firefox default again without losing anything. That's called in-place upgrade/repair and also works with Google Chrome and other non-browser apps.

RandySea · Aug 12, 2026

spapakons said:
But he wanted to keep everything, not only the bookmarks. I haven't worked with profiles, I don't use Firefox as my default browser, that's why I suggested to manually copy all the relevant folders before uninstalling both Firefox versions. I have done that many times. Once you copy the folders to their respective location on a new computer and then install Firefox, you have everything back.

In OP's case, once he uninstalled the undesired version of Firefox and the option to select Firefox as the default browser was gone, all he had to do was install Firefox again at the same folder as the desired version. Installer would detect the files and offer to upgrade. Proceeding with the "upgrade" would make Firefox default again without losing anything. That's called in-place upgrade/repair and also works with Google Chrome and other non-browser apps.

Not sure I follow which folders to move or copy where. I'll have to give this some more thought when my head clears of all the smoke. I mean that literally! I spent too much time outside this evening even with a mask on. I am in north central Washington, surrounded (at a distance) by serious fires.

idgat · Aug 12, 2026

RandySea said:
Then uninstalled the Firefox from the MS Store

Nope, use the forum favourite RevoUninstaller to remove ANY software. And don't forgett he advanced option to remove any leftover files, folders, registry entries that the basic uninstall process doesn't remove (otherwise the re-install will just re-assume those settings).

idgat · Aug 12, 2026

RandySea said:
Not sure I follow which folders to move or copy where.

No need to touch any individual folders

RandySea said:
Then uninstalled the Firefox from the MS Store.

Making a proper unnecessarily complicated mess of this, which should be a simple straight forward process, using (after the settings and favourites backup, of course) ...

Use the forum favourite RevoUninstaller to remove ANY software. And don't forgett he advanced option to remove any leftover files, folders, registry entries that the basic uninstall process doesn't remove (otherwise the re-install will just re-assume those settings)

Install and run RevoUninstaller
Options tab (along the top) > Uninstaller (LH column)
Untick Make a Restore Point before uninstall
Tick Checkmark all leftovers by default
Uninstaller tab > Double click the desired program
Run the uninstallation process
IMPORTANT
DO NOT reboot even if prompted when completed (Cancel if prompted)
Select the Advanced button and then run the process to remove all leftover files/folders/registry entries left behind after a normal default uninstall process
If prompted at any stage previously, now do the reboot

EDIT
If there are 2 FFx entries listed under the programs, do this for BOTH

EDIT 2
If one or both of the programs aren't listed in Revo, just re-install the appropriate version(s), and then do the proper Revo uninstall.

Secret Squirrel · Aug 12, 2026

spapakons said:
But he wanted to keep everything, not only the bookmarks.

A quick and elegant solution would be to use Firefox's built-in backup tool. It backs up bookmarks, settings, history, passwords, payment methods, extensions, and other browsing data. It might be useful for the OP or other folks, now or in the future. Here's the link.

spapakons · Aug 12, 2026

RandySea said:
Not sure I follow which folders to move or copy where. I'll have to give this some more thought when my head clears of all the smoke. I mean that literally! I spent too much time outside this evening even with a mask on. I am in north central Washington, surrounded (at a distance) by serious fires.

See the second paragraph of my reply. You had already uninstalled the new Firefox, the old one was working fine except Firefox didn't appear on the list to choose it as your default browser. All you needed to do was an in-place upgrade/repair to put the missing keys on the Registry and make Firefox appear on the list. You would then make it default and that's it. You wouldn't have lost any data.

Two versions of Firefox on new laptop, how to remove one?

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

Attachments

My Computers My Computers

At a glance

At a glance

Member

My Computer My Computer

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Venomous Member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

♦ ♦

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computer My Computer

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Active member

My Computer My Computer

At a glance

Well-known member

My Computers My Computers

At a glance

At a glance

Similar threads

My Computers

My Computers

My Computer

My Computers

My Computers

My Computers

My Computers

My Computers

My Computers

My Computers

My Computers

My Computers

My Computers

My Computer

My Computers

My Computers

My Computers

My Computers

My Computer

My Computers