How to move Firefox legacy extensions to another browser

Martin Brinkmann
Nov 14, 2017

Mozilla Firefox 57 will be released today; we have reviewed the new version of the web browser yesterday already. The new version comes with light and shadow; light, because it is faster and more responsive across the board, and shadow, because it dropped the old add-on system which Mozilla now calls legacy extensions.

All classic Firefox add-ons that are not WebExtensions at the time when you update to Firefox 57 are disabled automatically, and moved to the "new" legacy extensions section on about:addons.

While there is a chance that some may get updated to be compatible with Firefox's new extensions system, some won't.

That's bad if you rely on these extensions, and don't or can't use the browser without them. We published a guide on running legacy extensions once Firefox 57 comes along already.

As far as support for legacy extensions is concerned, here is a short table that highlights the situation:

  • Firefox 57 or newer -- Does not support legacy extensions. Nightly supports a switch for now, but many extensions don't work if you enable it.
  • Firefox ESR 52.*  -- The extended support release supports legacy extensions. It will do so until mid-2018 when the version of Firefox is upgraded to version 59.
  • Third-party browsers compatible with Firefox -- Pale Moon, Waterfox and SeaMonkey can run legacy extensions. In fact, some can only run legacy extensions and not WebExtensions.

Your options

Your two main options are to install Firefox ESR and use it for the time being, or use a third-party Firefox compatible browser instead.

You can run Firefox and a browser mentioned as an option above side by side. While this may not be practicable in the long run, it may help out some users.

Firefox ESR

Start by downloading a copy of Firefox ESR from the official website. Note that you should not simply run the browser on your system as it picks up the default Firefox profile by default.

You don't want Firefox ESR to use the same profile as other versions of Firefox. This means that you need to create a new profile for the browser and use it exclusively for it.

Tip: Check out our overview of Firefox command line parameters for additional information.

Here is how that is done:

  1. Select "custom" during installation, and make sure to select a custom directory for the ESR files.
  2. Uncheck the "launch Firefox now" option on the last installation screen and select Finish.
  3. Go to the installation directory afterwards and locate the firefox.exe file in it.
  4. You need to create a shortcut that points to the file now.
  5. On Windows, you'd right-click on firefox.exe and select "Create shortcut" from the context menu.
  6. Windows may not be able to create the shortcut in the folder. If that is the case, it suggests to create it on the desktop. Accept that.
  7. Right-click on the shortcut that you have created and select properties from the menu again.
  8. Locate the "target" field and append -no-remote -p to it. Make sure there is a space between the path and the new parameters, e.g. "C:\Program Files\Mozilla Firefox ESR\firefox.exe" -no-remote -p
  9. Close the window afterwards, and run the shortcut.

Firefox will launch the profile manager. Select "create profile" there and follow the profile creation wizard. I suggest you pick a descriptive name, e.g. Firefox ESR, to distinguish it from other Firefox profiles.

firefox ESR profile

Once you have created the profile, run Firefox ESR using it. Close the browser afterwards again. You can make things a bit easier now that you have created the profile:

  1. Right-click on the Firefox shortcut again and select properties.
  2. Append "profilename" to the command. Doing so will load the new profile automatically on start, so that the profile manager is not displayed anymore. Example: "C:\Program Files\Mozilla Firefox ESR\firefox.exe" -no-remote -p "FirefoxESR"

Moving legacy extensions

You have two options when it comes to installing legacy extensions in the new Firefox ESR installation. You can either do it manually, or use Firefox Sync for it.

Firefox Sync

firefox sync

If you don't use Firefox Sync yet, it may be your best option. Since you can also sync preferences, bookmarks and passwords, it is ideal if you need to move these as well to the new installation.

  1. In Firefox ESR, load about:preferences#sync and create a new Sync account (or sign in to an existing one).
  2. Select what you want to sync afterwards, e.g. only extensions, or other data as well.
  3. Start the other Firefox installation and configure Sync there as well. You can run these side by side on the same device thanks to the "no-remote" parameter.

The Firefox ESR version will receive any compatible browser extension afterwards. This includes legacy extensions. Note that it may not accept hybrid extensions such as NoScript.

You may need to install older versions of those extensions manually, as you cannot install these in Firefox ESR at the time.


firefox extensions

You have two options here: install the extensions from the Firefox profile folder of the regular Firefox installation, or download and install them from Mozilla AMO instead.

Note: Both methods won't install any customizations that you have made.

  1. In the regular Firefox version, type about:support and click on the open folder button when the page opens. This opens the Firefox profile that is used in the default file browser on the operating system.
  2. Open the extensions folder. Firefox lists all installed extensions in it.
  3. Open Firefox ESR, and load about:addons.
  4. Select the cogwheel icon and then "install add-on from file".
  5. Open the profile location of the regular Firefox version, and pick one of the extension files there.
  6. If you have difficulties identifying extensions, consult the extensions section on about:support and compare the IDs there with the file names.

You can go to Mozilla AMO alternatively and download extensions from there.

Third-party Firefox-compatible browsers

You may use Pale Moon or Waterfox instead if you don't want to use Firefox ESR. One reason for not wanting to use Firefox ESR is that it is only a temporary solution.

You don't need to create a separate profile for these, as they use their own profile folder.

There is no direct option however to import extensions to either browser. This leaves you with the manual options describes above.

How to move Firefox legacy extensions to another browser
Article Name
How to move Firefox legacy extensions to another browser
Find out how to move Firefox legacy extensions to another web browser to continue using them in that browser side by side with the regular Firefox version.
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  1. YSel said on January 5, 2018 at 9:32 am

    Here’s what I replaced from and to:

    Old — New
    RequestPolicy(Continued) —
    RefControl —
    Flagfox — Nothing
    IETab — Nothing

    Quantum is faster than old firefox. I should think these 2 add-ons are tradeoff…

  2. yereverluvinunclebert said on December 14, 2017 at 11:07 pm

    No need for Firefox anymore and it is such a relief. No need to imagine what they have broken now what they might break next. I have my firefox back in the shape of Pale Moon. I am SO happy. A died-in-the-wool firefox fan from the very beginning and I have abandoned my favourite browser of all time, never thought it would happen.

    How can the managers at Mozilla have brought it to this state?

  3. Martin S. said on November 29, 2017 at 1:27 pm

    Thank you!
    This helped me very much.

  4. DDL said on November 27, 2017 at 4:42 pm

    Firefox is going after what type of browser user?

    The ~40%, including the luddites and most elderly, who don’t use many if any addons?

    Preteens and teens, most who already prefer using mobile browsers on their smartphones, rather than PCs. tablets, or laptops anyway?

    Disgruntled Chrome/Chromium/Opera-like browser types? Opera went all in for the Chrome engine awhiile ago, which is when I stopped all use of it, later including Vivaldi.

    I don’t see how their userbase will grow to any significant degree, or even cover the tens, if not hundreds of thousands of fornerly loyal FF devotees, who will bid adieu and farewell, once Fixefox ESR no longer functions with legacy add-ons…including myself. Speed took a backseat to functionality, customization, and experimentation. I wasn’t losing a wink of sleep, just b/c FF was a few ticks slower, but I did when a few of their rapid-release updates killed some of my favorite themes and extensions in the past.

    But w/e…by mid-’18 I will have moved onto other browsers, some of which I have already installed and tried out briefly in the past.

    Perhaps in a few years, developers of Web Extensions will retore or revive some of the legacy extensions and maybe make me want to return to using FF as my primary browser agan…but IMO, it is far more likely that PCs and laptops will have become more obsolete. Just tether a smartphone to a HD screen, and you’re good to go @ home/work. Firefox for mobile might still survive.

  5. Marcin said on November 15, 2017 at 3:45 pm

    This list may interest some of you, regarding legacy extensions :

  6. aQ? said on November 15, 2017 at 1:03 am

    Anyone know how to change the “Download” button behavior to open in a newtab /instead of the popup/ like in TOR browser? “about:downloads”

  7. Mo said on November 14, 2017 at 5:45 pm

    Seamonkey is such an underrated browser!

    1. ponk said on November 14, 2017 at 8:49 pm

      If I recall correctly, there’s a post on Seamonkey’s website that it will follow Firefox and remove the legacy addons later.
      I also have doubts about Waterfox and Pale Moon, it’s hard to maintain a browser alone.
      It’s just delaying the inevitable.

  8. ilev said on November 14, 2017 at 5:45 pm

    “Start by downloading a copy of Firefox ESR from the official website”
    Download a copy of Firefox ESR portable from PortableApps.

    1. Clairvaux said on November 14, 2017 at 5:52 pm

      Why ?

  9. Clairvaux said on November 14, 2017 at 5:43 pm

    Another incredibly useful and timely article. I have now installed both FF 56 with “never update”, and FF ESR 52.4.1 (not running at the same time), so a few questions.

    – When browsing the new Mozilla add-on repository with ESR 52, most (all ?) add-ons tell me : you need to download Firefox to install this add-on. Even some that are not Web Extensions, and therefore should be compatible, shouldn’t they ? Some of them even incorrectly identify my FF version as a much older one. This does not happen with regular FF 56. What’s afoot ?

    – It’s my impression that the add-on repository has been nuked clean. It seems to me there are much less add-ons than before, even though one can still find there non-Web Extensions which announce they won’t be ported. Is that correct ? Does that mean that users who did not, and won’t make the jump to Quantum, are left with old extensions which are now gone, and they can’t reinstall, unless they can be downloaded from their own web page ?

    – What is the difference between “featured”, “top-rated” and “trending” extensions ? When clicking on the “bookmarks” tab, then on “see more”, I only find 2 “featured” bookmark-related add-ons, 25 “top-rated”, and 25 “trending”. Is that all ? Also, among them, there are legacy extensions that will die.

    – About the -no-remote switch. Is it necessary to use it even though you don’t run two instances of Firefox at the same time ? Do you need to apply it to both (or all) FF executables ? Does it matter if one of those Firefox instances is your default browser ? Does it matter if -no-remote is on the left or on the right of the -p switch ?

    Thank you for any light on this.

    1. Jody Thornton said on November 15, 2017 at 8:36 pm

      There must be tons of add-ons that don’t even run with 52 ESR (or before even). On Pale Moon, I run FoxE9, which gives the appearance of Internet Explorer 9. Since Australis came along, that has been incompatible with Firefox.

      There must be hundreds of add-ons like that.

  10. Tim Parsons said on November 14, 2017 at 4:17 pm

    I’m slowly migrating my systems to Waterfox — I don’t have so many addons that it’s particularly painful, although the process of exporting settings from the addon in Firefox and importing them to a newly installed addon in Waterfox is showing some instances where the process isn’t quite as successful as you might hope…

    But the main reason for posting here is: are we just delaying the inevitable?

    My favourite ui addon is Speed Dial. For all that there’s a dozen ways I could achieve something similar, the ability to have a series of themed tabs with all my goto websites in a grid of thumbnails is something I’ve got very, very used to. I’ve tried going back to bookmarks, or using some other dial-ish solution and nothing else comes close. But there’s no sign of it being developed further or reengineered for compatibility and I’m quite sure there’s a hundred other addons that people have got used to and built workflows around that are also soon going to stop working in Firefox.

    Presumably there will come a point — if it hasn’t come already — where the developers can only justify the effort if they’re working somewhere near where the majority of people want to be…?

  11. Goldendays said on November 14, 2017 at 4:09 pm

    Not so sure any of this is a solution. I’ve maintained my Cyberfox installation and profile with all of the extensions I needed or preferred. Lazarus, for instance, still works on Cyberox, but it doesnt’ work in Waterfox. FEBE works great for importing a profile if one still has a running, viable FF based browser.

    I found Pale Moon to be not worth the trouble since so many, at least 50%, of the extensions I use were incompatible with the current build.

    It’s a mess, but Nightly 59 shows promise as more extensions become available.

  12. Mike J. said on November 14, 2017 at 3:50 pm

    I see references to how much faster Chrome is than Firefox. I use Iron & Waterfox on a daily basis, and can really tell no difference in speed. I don’t have a ton of extensions, & I always do the optimizing ritual in about:config that’s been around for a decade. ( I have no idea if it is still necessary, but it makes me feel good.)

    1. anon said on November 14, 2017 at 7:50 pm

      On the Mac sware iron is certainly faster. FF is getting there but is averaging 0.7s slower page loads over all the ones I timed. That doesn’t sound like much but you do notice it, you might ignore it if it gave you something extra over iron but it doesn’t any longer. It’s just a slightly faster dumbed down version that lost practically all the resons you used to want to use it.

    2. Tom Hawack said on November 14, 2017 at 4:00 pm

      Of course there’s no difference, perceptible anyway, especially since Firefox 55.
      Chrome’s speed is a myth among many others. Fill Chrome with as many add-ons and tweaks as Firefox and I’ll eat my hat if Chrome isn’t slower and doesn’t more RAM.

  13. Marcin said on November 14, 2017 at 3:15 pm

    Thank you for your valuable articles about Firefox, as usual, Martin.
    I have just made a backup of FF56 to prevent any disappointement.
    Checking for update now, FF still says 56 is up to date. Waiting…
    I think I will need some time to take a final decision, but Pale Moon looks like the best alternative for my needs from what I I’ve read.

    1. Doc said on November 14, 2017 at 5:11 pm

      Pale Moon is woefully behind, and many addons see the “27.x” version number and won’t install or run properly. I used CyberFox until the developer hung up his hat (too busy or ill to continue), and switched to Waterfox; I’ve been quite happy except for the poor Flash performance (I’ve started using Chrome just for gaming).

      1. anon said on November 14, 2017 at 7:54 pm

        If you care about the extension situation then PM doesn’t really improve anything unless you’re lucky. Waterfox does seem the better bet at the moment even if it’s just a stop gap.

      2. Marcin said on November 14, 2017 at 5:36 pm

        Firefox 57 has now landed here. Disaster :-/
        Thank you for your opinion Doc, though this is not very encouraging…
        I will also try Waterfox in the coming days, aside Pale Moon.

  14. It's a me, Mario! said on November 14, 2017 at 2:55 pm
    1. Martin Brinkmann said on November 14, 2017 at 3:18 pm

      Watching this like a hawk, still no sign of the release.

      1. Curtis K said on November 21, 2017 at 4:33 am

        Is out now.

      2. Martin Brinkmann said on November 21, 2017 at 7:07 am


      3. Pants said on November 15, 2017 at 6:13 am

        Good – stick to your hawk and leave my eagle’s eyes alone :)

  15. Clas said on November 14, 2017 at 2:10 pm

    nice article. i left firefox long ago for palemoon …stuck with that up to 26.5 and no further because of extensions not working….but that one works great as install or portable. now run both palemoon 26.5 portable and waterfox portable. they run on a 2.0 usb port on a flash drive and both are fast, peppy, and have all i want or need in a browser. both are run sandboxed and never a problem at all. both use about 400-500m ram with a bunch of extensions which all work great. all videos and sites run perfectly. firefox never listened…like the nfl kneelers…so i quit them and never looked back..good luck to all.

    1. Doc said on November 14, 2017 at 5:08 pm

      You don’t actually have to run Waterfox Portable, the PortableApps suite, etc. on a USB drive, you know; they work just fine from a hard drive or SSD. (I usually run mine from a D: partition so if I need to reinstall Windows, I can just wipe the C: partition and keep my portable apps).

  16. TelV said on November 14, 2017 at 11:36 am

    I’m a little confused re: Waterfox. Some advice please.

    On the blog site: it states that the current release 55.2.2 contains security patches to maintain compatibility with FF56. No problem there.

    It then goes on to state that version 56 will be released mid- or end October so assume there’s just a slight delay there. But it further mentions, quote: “56 will remain as ESR version for the foreseeable future, keeping updated with security patches”. Does this mean there are going to be two different releases of Waterfox i.e. a standard version and an ESR? In that respect there’s also mention of a “new” browser. Should I take that to mean there will be a new browser and Waterfox ESR as well, or are they both one and the same animal?

    1. Appster said on November 14, 2017 at 11:59 am

      There will be two different versions of Waterfox: A Waterfox 56 ESR, which will only receive security patches, and a “new browser”, which will be a new form of Waterfox based on Firefox Quantum. As far as I know the Waterfox dev plans to extend the WebExtensions APIs in the new browser, which is something I am pretty excited about.

      1. Tom Hawack said on November 15, 2017 at 9:44 am

        @Appster, good news indeed which heals the frustration of having to wait so long for this Waterfox 56 — I’m not complaining but the developer had announced first the end of October as the release term, then November 11th (the end of the announcement weak, even if it was implicitty a “maybe”) … anyway better late and good than an approximate update, of course. It’s not that I’m obsessed by updates as such but in my case I have two add-ons which require Firefox 56 APIs … and as many the world turns around my belly of course.

        Thanks for the info.

      2. Appster said on November 15, 2017 at 12:00 am

        @Tom Hawack: Good news, Waterfox 56 with FF57 security patches will release pretty soon.

      3. Tom Hawack said on November 14, 2017 at 12:31 pm

        @Appster, it’s more a hope than a guess here. May you be right.

      4. Appster said on November 14, 2017 at 12:24 pm

        @Tom Hawack: My best guess is that he won’t do that. Maybe he is releasing a Waterfox 57 unstable build with Australis, if anything.
        I am not getting this obsession with (perceived) speed, it seems rather stupid to sacrifice actual functionality for that.

      5. Tom Hawack said on November 14, 2017 at 12:06 pm

        As I understand it it’s more a questioning than a road-map :
        “Plans for upgrading Waterfox to use newest Firefox Quantum update?”

        Some Waterfox users are so thrilled by the magnificence of the “Quantum” aura that they forget that many other users have adopted Waterfox less to be a Firefox follower than to allow legacy add-ons to survive.

      6. TelV said on November 14, 2017 at 12:05 pm

        OK, so the ESR version will be the one which supports FF legacy extensions I assume.

  17. T J said on November 14, 2017 at 10:14 am

    Martin, thank you for yet another excellent blog. This will help all FF users, even the power users, if they decide to use a different browser. It is precise, concise and the screen grabs make it easy to understand the steps required to simplify the porting of profiles.

  18. Appster said on November 14, 2017 at 9:11 am

    @Martin Brinkmann:

    > There is no direct option however to import extensions to either browser. This leaves you with the manual options describes above.

    This is incorrect. Waterfox (since ver. 55) has a migration tool built-in that will import extensions on first startup. It gives you the option to choose between this or and creating a completely new profile. Please correct this.

    I find this way more recommendable than the whole Firefox 52 ESR shenanigans, especially since one can‘t know whether or not the locally saved XPI extension files are still compatible with this version without having previously checked this on AMO. You may wish to add a remark about that, too.

    1. Jody Thornton said on November 14, 2017 at 3:24 pm

      (Afterwards @Appster – I realized that this was about the migration of extensions, so my bad)

      Also SeaMonkey has a tool that MAY be able to run Firefox extensions on SeaMonkey, though the results aren’t universally acceptable. But it’s another option.

    2. Martin Brinkmann said on November 14, 2017 at 11:41 am

      Can you run the tool again afterwards? I checked the import and export option, and Firefox was not listed as an option.

      1. Appster said on November 14, 2017 at 11:53 am

        I am not aware of any option to run it after first startup. “Import from Firefox or earlier Waterfox” should be the first option, at the very top. Odd that you are not getting it, because many people actually migrated this way. Do you have your profile in a non-standard location?

    3. apopo said on November 14, 2017 at 11:24 am

      Did Martin ever correct mistake on article before?

      You can also use FEBE to backup and restore profiles easily

      1. Tom Hawack said on November 14, 2017 at 11:54 am

        Don’t use FEBE, don’t copy, restore to transfer a backed-up profile from Firefox to Watrfox! Add-ons have their settings which for some of them are dependent/related to te browser, even to its version. Copy/pasting is a facility which is NOT adequate when the concern is a browser profile from one version to another, hence even less when from one browser to another. Generally speaking copy/paste may be dangerous : I’ve seen users i.e. restore the entire Windows’ ProgramData folder after having updated their OS! You just cannot consider copy/paste as a panacea, be it with FEBE. I mean : install from scratch, where’s the problem?

    4. Tom Hawack said on November 14, 2017 at 10:23 am

      I’d be very cautious when it comes to using Waterfox’s migration tool. At least I’d recommend using it *only* with the same version of both browsers : if Firefox version is > or < 55 (present version of Waterfox) don't use the migration tool but re-install add-ons from scratch (bookmarks, places.sqlite, may be copy/pasted).

      In fact I'm not even sure that Waterfox install proposes the migration feature if versions differ. I know that I had installed Waterfox 55 when my Firefox version was ESR 52 … and I hadn't met the migration tool, which happened to be a good thing. A clean install is always better IMO, I did it with 70 add-ons so with less it should be a few hours' work, but worth it. I've read on Waterfox's Reddit pages too many users describing problems which in fact were only caused by migration, copy/paste etc : do a clean install and you'll encounter no problem with Waterfox.

      1. Appster said on November 14, 2017 at 11:57 am

        Tom, this remark was about the existence of the migration tool only, it doesn’t judge whether or not it is advisable. It worked perfectly fine for me, at least. Many errors come to pass because add-ons are storing their data in non-standard locations. The migration tool can’t cover those special, add-on specific cases. And of course some people were having their profiles in non-standard locations, which is also something the tool is of course unable to cover. Anyways, I agree with you that setting up a new profile would be better in most cases.

  19. P. M. Claarke said on November 14, 2017 at 9:02 am

    In before we get another plethora of posts of users telling us how happy they are now that they are on Chrome.

    Why won’t they never leave these articles about Firefox?

    1. anon said on November 14, 2017 at 3:30 pm

      You’re the only who has even mentioned chrome so you’re the only offender.

      1. 88 said on November 14, 2017 at 4:06 pm

        You nailed it !! :)

  20. Robert Ab said on November 14, 2017 at 7:54 am

    Thank you. This is really great article.

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