Mozilla plans to update Firefox's data synchronization feature in version 29

Martin Brinkmann
Jan 12, 2014


Firefox Sync, the web browser's data synchronization feature, is not overly popular according to Mozilla. Only 1% of all users have it enabled, and of those, only 20% have set up a second device with which data is synchronized.

At the time of writing, data such as bookmarks, passwords, installed add-ons, tabs, the browsing history and installed add-ons can be synchronized between devices.

Mozilla's main motivation to improve Sync is to make it easier for users to set the system up, as it believes that it is the main reason why Sync is not used by more users of the browser.

Besides improving the usability of Sync, improvements are also desired in terms of quality and scalability of the service. Mozilla notes that its Sync servers are failing too frequently, and that the existing codebase is not adequately addressing "the reliability, performance, fault recovery, and efficiency requirements" of high-usage systems.

The current version of sync is also limited in terms of features that can be added to it, and this is also something that Mozilla wants to change as it puts Firefox's synchronization feature at a disadvantage when compared to other browsers.

Firefox Sync 1.5

The current plan is to ship Firefox Sync 1.5, the current version is 1.1, with Firefox 29. The goal is ambitious, considering that code will be frozen for that version of Firefox on January 29th.

The browser version itself will be released on April 29, 2014, and while time is limited, it is likely that Mozilla will improve the feature in the Aurora and Beta builds of Firefox 29.

The time constraints to mean that Firefox OS and the Modern UI version of Firefox for Windows 8 won't be supported initially by the new Sync.

What it means for existing users

Things do get a bit complicated for existing users, as it is not possible to easily migrate them from one Sync version to the next.

When Firefox 29 comes along, nothing at all will change for existing Firefox Sync users. Users who have not configured Sync yet will be introduced to the feature. This happens for instance on the new tab / home page.

Existing users can add new devices to Firefox Sync up until Firefox 28. This won't be possible anymore in Firefox 29, which may cause some confusion depending on how well -- or at all -- this is explained during the setup.

Starting with Firefox 29, it is no longer possible to create new Sync 1.1 accounts. From that version on, only new Firefox Sync 1.5 accounts can be created.

There is no option to sync data between a device running a Sync 1.1 account and another that is using the new synchronization version due to differences in data handling and storage.

Starting with Firefox 30, existing Sync users will be migrated to the new version, while the old Sync will be retired when Firefox 31 comes along.

What this means basically is that existing Sync users need to create a new Sync account and use it from that moment on. Once the New Sync account is created, it can be used like the old one. It is however necessary to set it up on all devices that need to be synchronized.

Self-hosted sync servers

Firefox Sync 1.1 allowed you to run your own sync-servers. The feature will theoretically be also available as part of Firefox Sync 1.5, but it will not be released right away with the Sync 1.5 update in Firefox 29.

  • Some unknown proportion of the user base uses their own Sync servers (whether as enterprise deployments or self-run home-network setups). These users probably (a) don't want to migrate, (b) have nowhere to migrate to yet. [Asa] I don't think we should worry too  much about this group. If we can identify them and message them that'd be sufficient for my concerns.

New Sync setup flow

To set up a New Sync account in Firefox, the following needs to be done:

  1. Click on Create Account link to get started.
  2. Enter email address and password for the Sync account (not the email password).
  3. Confirm the email address.

Once verified, the account can be used on other devices to enable synchronization. (via Sören Hentzschel)


All in all, it is up to Mozilla to explain to users why it is necessary to update Firefox Sync in a way that it is no longer compatible with the previous used version.

If that is not handled well, it could irritate users who are using Sync currently. This is also true for Sync users who use self-hosted servers, as they won't be able to continue using them in the way they are setup currently when the New Sync is launched.


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  1. Germán said on January 27, 2014 at 4:01 am

    I am one of those 0.2% users who have enabled and used Firefox Sync on different devices. Over the years I have found some problems and limitations (synchronizing tabs is not very ergonomic, there seems to be a max size on some kind of synchronization transfer, so that for sync my own ABP filters I have been using another tool … ) . For simple things, like sync bookmarks, the tool worked OK.

    Either way, after this Snowden summer … things are changing in my mind. The last straw was this article ( ) from Andreas Gal and Brendan Eich . I appreciate their honesty when they remind us things like “the government may force service operators to enable surveillance”.

    So for me there is not going to be ‘Firefox Sync’ anymore … I leave the boat … and yes, the reason is PRIVACY.

    I know the data is encrypted before leaving the client and so that it’s stored on Mozilla servers encrypted, but … if the federals were able to force Ladar Levison to open the can …

    I am sorry.

  2. Teiji said on January 17, 2014 at 1:00 am

    I’ve been using Sync since it first releases. I do agree that the setup is confusing, but after that sync does its job (albeit the server downtimes mentioned in this post). So I’m looking forward to this new version of Sync with simplified setup.

  3. Don said on January 13, 2014 at 9:45 pm

    I’ve been a happy user of Sync for several years. I needed to wait until I had an encrypted profile at work. I admit that there are oddities after doing some bookmark reorganizing. But I no longer have any issue now that I just use tags. And having a combined history and all passwords is a great convenience!

    I’m a little unnerved by this “update” to Sync 1.5.

  4. Nicolas Steinmetz said on January 13, 2014 at 12:07 pm

    So looks I’m an exception to run my own sync instance and connected over 4 devices. I tested it first on Moz Sync Server and as it was working well, I moved to my own instance a few weeks ago.

    Even if I agree it can be improved (even if you are familliar with python, not straight forward to install and run it ; a UI could be useful too, if there is one I did not find it) but at the end, it works as a charm.

    I’m reluctant to go back to moz sync servers as I want to own my data. So I really hope Mozilla will maintain the self hosted capacity of Sync and not let its users on the side of the road by providing a client that could no longer use the current sync implementaiton if they don’t provide a self hosted new sync version.

    For the migration, I’m fine if it’s to drop the current version and sync with the new one if there is no data loss and improvements.

    What’s the best way to share my opinion with the people in charge of sync ?

  5. Zeal0us said on January 13, 2014 at 6:54 am

    It was a pain in the ass to use. I wish Mozilla could do something similar to Google and just allow me to sign in, automatically download my addons, download my bookmarks and update my save password list.

    1. Caspy7 said on January 13, 2014 at 7:27 am

      That’s what this is. The new version is just like that.

  6. Karl Gephart said on January 13, 2014 at 1:43 am

    A couple years ago, I used sync to move all my stuff from Win to Ubuntu. My stuff got moved the wrong way and hosed my Win Firefox despite me double-checking my directional settings, so I’d be very skeptical to try it again. Right now, I’d just be happy to have Firefox on iOS.

    1. Caspy7 said on January 13, 2014 at 8:18 am

      Apple does not allow *any* natively implemented browsers. All alternate browsers (including Chrome) are merely skins that embed iOS’s webkit engine. So it’s a matter of picking the UI you like.
      One major caveat though: Only Safari is allowed to use the Nitro Javascript compiler. Meaning that all the skins run Javascript much slower than Safari. You can test this out by running a JS speed test in Safari and then in any alternate browser (which will show it to be *much* slower).

      Do a search in the iTunes store for ‘Firefox’ and you’ll find a few skins that sync using Firefox’s Sync. Some are pay, some are free. I’d just make sure to compare the ratings and reviews.

  7. WandersFar said on January 13, 2014 at 12:27 am

    I tried Sync years ago when it first came out, but I grew frustrated with it since, at the time, it didn’t sync keyword search engines. (For example, if I’d set up ‘t’ as a keyword for, Sync wouldn’t propagate the change on other computers running the same profile.) I’m not sure if this issue has been resolved in later versions, but I’ve long since abandoned the service as that was the whole appeal of it in the first place.

    I found it was a lot easier to just keep a backup profile in my Dropbox and copy it over to new Firefox installations as needed. It’s handy for reverting unwanted changes, too.

  8. uluwatu said on January 12, 2014 at 11:00 pm

    This is so typical of Mozilla.

    – What about the power users?
    – Who cares? Let’s just ignore them and ‘that’d be sufficient for my concerns.’

    1. hum said on January 14, 2014 at 10:59 am

      It’s not exactly news that Mozilla in general and Doetzler in particular are absolutely positively hating the power users. Every new version with nonsensical chances and feature-removals is proof of that.

    2. Sören Hentzschel said on January 13, 2014 at 3:38 pm

      uluwatu, the development of Sync is NOT finished after the release of Firefox 29…

      1. Sören Hentzschel said on January 13, 2014 at 7:21 pm

        Mozilla will introduce the new Sync in Firefox 29. The old sync will work till Firefox 31. At least. So there are at least two more cycles for remaining stuff. And by the way, Mozilla says (in the Wiki): “Custom servers should in theory be possible with FxA Sync, but with a different architecture (Token server + Sync 1.5)”.

      2. uluwatu said on January 13, 2014 at 7:02 pm

        But people who use it now will be forced to go by without an important, privacy and security related, feature for unforeseeable future (if Mozilla tough the users anything it’s the fact that they don’t keep schedule)

    3. Martin Brinkmann said on January 13, 2014 at 5:29 am

      I do not understand why they rush the feature. Instead of rushing it, they should make sure it ships with everything that the current sync has to offer.

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