Firefox Preview 4.0 Stable brings uBlock Origin support

Mozilla released Firefox Preview 4.0 on March 9, 2020, the latest stable version of the upcoming re-interpretation of Firefox for Android. The new browser version is only available on the project's GitHub webpage at the time of writing and not on Google Play.
The Google Play version is at 3.2.1 currently while the GitHub version brings the version of the mobile browser to 4.0. Users who want to upgrade to the new version of Firefox Preview Stable right away may download the APK file from the releases page and install it manually. It is necessary to allow the installation of apps from unknown sources to do so though.
Mozilla highlights several new features in Firefox Preview 4.0 including initial extension support, inclusion of the uBlock Origin extension by default, improved login management, and options to bypass certification errors.
One of the main new features of Firefox Preview 4.0 is initial support for browser extensions. While officially limited to the content blocker uBlock Origin, Mozilla promised that it would improve support throughout 2020 to integrate full extensions support in the new mobile Firefox browser.
The uBlock Origin extension is not enabled by default but Firefox Preview users may enable it by selecting Menu > Add-Ons Manager > uBlock Origin. The list of permissions the extension requires is displayed then and a tap on "add" enables the extension in Firefox Preview. The extension can then be managed via Firefox's main menu button. It is a bit harder to manage sites in the extension because of that but all functionality appears to be available.
As far as other major improvements are concerned, there are a few in the release:
- Login Management improvements -- Firefox Preview users may save and autofill logins, copy logins to the Clipboard, delete them, and perform other basic operations on the saved logins of the browser.
- Top Sites --Top visited sites and favorite sites are now displayed on a New Tab Page. Options to remove top sites are included.
- Bypass Certification errors -- Certain certification errors may now be bypassed.
Now You: have you tried the new Firefox Preview already? What is your impression?


thanks you saved my 1000 tabs :)
Fantastic! Thank you! This worked like a charm. Had exactly the same issue in Firefox on a PC and this fixed it.
Thank you for sharing this! Like you, I’d noticed that disabling/re-enabling the extension would work for that browser session, but I hadn’t tried anything yet to force a fix. I’m SO glad it was this easy!
I sure hope the OneTab team issues an official fix ASAP, though. Now that it’s been a few days, they’re starting to get bad reviews, which is unfortunate.
Yes! I also tried the workaround. I also reported this bug to OneTab team on the first day I faced this issue.
Thanks, Ashwin for the fix!
I was nearing desperation when I found your direction. It worked.
Thank you so much.
Hi, OneTab developer here. Sorry for this – it’s not clear why this bug is suddenly happening for some people, but we’re urgently investigating this with the Mozilla/Firefox team and will be providing a fix very shortly.
Thank you so much for sharing this fix! You saved my tabs. The only note/point I would like to add is for Step 2.
Perhaps put a note stating they should copy Step 3 and forward of your tutorial to Word. Once we close Firefox, we lose visibility to your tutorial. For me, I know I would not be able to remember the .bkp.
Again, thank you!
Easy temporary fix: To make OneTab work again, type “about:addons” in your Firefox address bar. Then find OneTab in the list of extensions, and click the blue toggle button twice. This will disable and then re-enable OneTab, and cause it to work again.
We’re working with Mozilla for a permanent fix. Sorry for the inconvenience, this is a very strange issue that is only affecting the Firefox version of OneTab.
I have found by disabling and then re-enable in the add on menu I get my tab back. Short term fix. Will try yours.
Thank you. I thought I had lost a month of digging. I’ll be a little more attentive about exporting the urls from the extension list now. It’s a great tool but Firefox doesn’t always play nice with its extensions.
Good news – I’ve been working with Mozilla all morning to resolve this. Mozilla have confirmed it was due to a bug in Firefox (related to extension permissions downgrades).
To fix OneTab, just go to “about:addons” in your Firefox address bar, click the ‘cog’ icon in the top right, and click ‘Check for updates’. This will upgrade you to OneTab v1.39, which fixes the issue.
Darn, I tried everything here and I still can’t get my tabs back. I even did a full system restore to a point last week hoping that my saved tabs would be in the old .xpi file, but no luck.
I’m pretty disappointed :(
Probably I should’ve been more patient, but now I don’t know how to feel about this. I lost about 900 tabs in the recovery process (I reinstalled OneTab), which, incredible as it sounds, weren’t all just a messy dump I’m never going back to, but actually important stuff (yeah, I have a peculiar workflow).
Trying to suppress the anger and reflecting on what happened, it seems I should blame myself for not having a backup. But surely I couldn’t back it up manually every time I save a tab, it would defy all purpose of having this addon in the first place. A couple of years ago data was stored at “~/.mozilla/firefox/%PROFILE%/jetpack/[email protected]/simple-storage”, and you could back it up with simple crontab. This is no longer the case, this folder is just empty. And since OneTab is closed-source black box, I couldn’t have done anything else as well.
So the only reasonable lesson to be learned is that I actually must stop relying on OneTab, since sooner or later it will let me down again. Fuck it.
I just disable and re-enable. No tabs lost!
I switched from OneTab to Tab Stash (https://addons.mozilla.org/en-US/firefox/addon/tab-stash/) months ago and haven’t looked back. I had never experienced any data loss with OneTab, although I was a bit concerned by some reports of data loss I read about. My main issue was with OneTabs performance, it’s a hog. I had been looking for a replacement and testing out a ton of addons for a couple of months when I finally discovered Tab Stash, and am damn glad I did. I really can’t recommend it strongly enough…
Thanks, bsdaddict. Never tried it, looks nice, but I’m a bit concerned by small number of stashed tabs on these screenshots, not sure if it’d be usable when stashing a lot of tabs. How many tabs do you usually have stashed?
Tab Stash is is a great alternative to One Tab, y’all… I made the switch months ago and am very happy with it.
>DO THIS FIRST: Before trying the following fix, I recommend disabling OneTab and re-enabling it from the about:addons page, to access and regain your tabs.
Worked for me! Many, many thanks!
I know it’s late but ist there an option for chrome on android tablets aswell? My wife hates it that the search bar and Tab list will just come Up again when she Scrolls up
You are truly a hero and a scholar, sir or madam. I salute you!