Transitioning Legacy Sync users to Firefox Accounts

It has been almost a year since the release of Firefox Accounts and the new Firefox Sync service, and the response from users has been very positive.  The simplified setup process has made it easier to get started with the system, to connect new devices, and to recover data if a device is lost — all of which has lead to the new system quickly gathering more active daily users than its predecessor.

During this time we have kept the legacy Sync infrastructure in place and working as usual, so that users who had set up Sync on older versions of Firefox would not be disrupted.  As we begin 2015 with renewed focus on delivering cloud-based services that support the Mozilla mission, it’s time to help transition these users to the new Sync system and to Firefox Accounts.

Users on legacy Sync will be prompted to upgrade to a Firefox Account beginning with Firefox 37, scheduled for release in early April.  There is a guided UI to make the experience as seamless as possible, and once complete the upgrade will be automatically and securely propagated to all connected devices.  Users on older versions of Firefox will see a warning notice and will be able to upgrade manually.

The legacy Sync servers will remain available during this time to help ensure a smooth transition.  We will monitor their ongoing use and decide on a timeline for decommissioning the hardware based on the success of our transition strategy.

We’re looking forward to introducing more users to the improved Sync system, and to rolling out more services for your Firefox Account in 2015.  Don’t hesitate to reach us on or in #sync on IRC with any questions or comments.




  •  When will the legacy Sync servers be switched off?

We expect to decommission this infrastructure before the end of 2015, but no firm date has been set.  This decision will be based on ongoing monitoring of its use and the success of our transition strategy.

  •  What about Extended Support Release (ESR)?

Users on the ESR channel will start seeing the upgrade prompts in Firefox 38, which is scheduled for release in early May.  We are committed to maintaining the legacy sync infrastructure until previous ESR versions reach end-of-life on August 4.

  • Will my data be automatically migrated to the new servers?

No, the strong encryption used by both Sync systems means that we cannot automatically migrate your data on the server.  Once the account upgrade process is complete, Firefox will re-upload your data to the new system (so if you have a lot of bookmarks, you may want to ensure you’re on a reliable network connection).

  •  Are there security considerations when upgrading to the new system?

Both the new and old Sync systems provide industry-leading security for your data: end-to-end encryption of all synced data, using a key known only to you.

In legacy Sync this was achieved by using a complicated pairing flow to transfer the encryption key between devices.  With Firefox Accounts we have replaced this with a key securely derived from your account password.  Pick a strong password and you can remain confident that your synced data will only be seen by you.

  •  Is the new Sync system compatible with Firefox’s master password feature?

Yes.  There was a limitation in previous versions of Firefox that prevented Sync from working when a master password was enabled, but this has since been resolved.  Sync is fully compatible with the master password feature in the latest version of Firefox.

  •  What if I am running a custom or self-hosted Sync server?

This transition affects only the default Mozilla-hosted servers.  If you are using a custom or self-hosted server setup, Sync should continue to work uninterrupted and you will not be prompted to upgrade.

Although we have no plans or timeline for doing so, it’s likely that support for the legacy Sync protocol will be entirely removed from Firefox at some point in the future.  You should consider migrating your server infrastructure to use the new protocols; see below.

  •  Can I self-host the new system?

Yes, either by hosting just the storage servers or by running a full Firefox Accounts stack.  We welcome feedback and contributions on making this process easier.

  •  What if I’m using a different browser (e.g. SeaMonkey, Pale Moon, …)?

You should consider hosting your own server to ensure uninterrupted functionality.

3 responses

  1. Matt A. Tobin wrote on :

    Most users of the Pale Moon browser /should/ already be on our project provided sync server. However, if you are a Pale Moon user watch for an announcement from us via Pale Moon’s site and forum. and respectively.

    Matt A. Tobin
    – Add-ons Site Administrator and Team Leader
    – Core Contributing Developer / “Comm” Codebase Engineer
    – IRC Channel Coordinator ( #palemoon)

  2. Justin Wood (Callek) wrote on :

    To be clear, SeaMonkey is in talks for what it would mean for us to upgrade our Project to using the new Sync engine/servers/etc. In terms of Maintenance burden to Mozilla, user sovereignty, and user confusions among branding (among some other concerns).

    We’ll provide more information on our end when/if we have “New Sync” support in SeaMonkey. In the meantime, if you don’t need to have SeaMonkey Sync linked up with Firefox Sync you have no need to host your own servers *until* Mozilla decommissions those legacy Servers

  3. John Hesling [:John99] wrote on :

    You mention ensuring users with bookmarks synced will need a relible connection. Is that sufficient advice?

    Might it be an idea to specifically advise users to manually backup their bookmarks prior tothis transition.
    Link for instance to our Mozilla (Sumo) help article [1]

    End uses will not be interested in technical details and should not ordinarily post in bugzilla [2] but there are well known issues (bug621584)[3] with Sync corrupting bookmarks listings, and this is increasingly likely to occur on attempting to handle larger Syncs merges of bookmarks as potentially will occur here.

    3[meta] Bookmarks are duplicated, reordered and moved

    No preview option when posting on this blog. So not possible to check on allowable markup.