Here is what you need to know about the 2020 Firefox for Android upgrade

Mozilla is working on a new mobile browser for Android that is called Firefox Preview currently. Firefox Preview is in development at the time of writing and available as Stable, Beta and Preview channel version.
While it is in preview, the classic version of Firefox for Android remains the main mobile browser by Mozilla; this is going to change in 2020 when classic Firefox will be migrated to Firefox Preview (which, I suppose, will be renamed to just Firefox then).
Important: the requirements for the automatic upgrade from current Firefox to Firefox Preview are that the mobile device runs at least Android 5 and that the installed version of the Firefox browser is at least 59. If the requirements are not met, Firefox won't be upgraded to the new version.
Mozilla plans to migrate Nightly users first. If Firefox Nightly is installed on a device that meets the requirements, it will be upgraded to Firefox Preview "in early 2020". A date has not been set yet and Mozilla does not mention the channel that Nightly users will be migrated to but it is almost certain that they will be migrated to the Nightly version of Firefox Preview.
In Spring 2020, Firefox Beta installations and Firefox Stable installations will be migrated to Firefox Preview if they meet the requirements.
Once migrated, there is no option to rollback to the previous version of Firefox. Android users may want to consider creating backups of Firefox or the entire system before the migration happens.
The following items will be migrated:
- Open Tabs.
- The browsing history.
- The bookmarks.
- If Firefox Account is used, it will be migrated.
- Cookies and "partial browser cache".
- The uBlock Origin add-on.
- Saved logins if no master password is used.
These require some explanation. The initial version of Firefox Preview for Android comes with limited support for add-ons. Only uBlock Origin will remain enabled after the migration, any other add-on that is installed will be disabled; this is temporary only according to Mozilla. The organization wants to add support for more add-ons in upcoming releases and enable full add-on support in late 2020.
Since logins are not migrated if a master password is set, it is advised to either back up the logins or disable the master password before the migration happens to ensure that the logins are migrated.
Google Search will be set to the default search engine during the migration. Users who want to use a different search engine need to change it after the migration.
Firefox Preview for Android offers better performance and security according to Mozilla. The mobile browser includes support for tracking protection, collections and new customization options.
Some features that were available in the previous versions of Firefox for Android may not become available of they "weren't frequently used".
Now you: what is your expectation when it comes to Firefox Preview?


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!