The old Sync system and account portal have been deactivated on September 30th 2015 and replaced with Firefox Accounts-based Sync.

Firefox Sync lets you access your information on all your devices. The new, Firefox Accounts-based Sync, released in April 2014, makes set-up even easier. All you need is an email address and a secure password to synchronize your information - no device codes needed.

How do I upgrade to Firefox Accounts-based Sync?

Follow these instructions to update to the new Sync system.

Is my data 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).

What about Extended Support Release (ESR)?

Users on the ESR channel have support for Firefox Accounts and the new Sync service as of Firefox 38. Previous ESR versions reach end-of-life in early August and we encourage all users to upgrade to the latest version.

Is the Firefox Accounts-based 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.

Are there any security concerns with upgrading to Firefox Accounts-based Sync?

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 old 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 is safe from prying eyes.

Do I need to take any precautions before upgrading? I sync bookmarks.

Yes, it does help to ensure you have a reliable internet connection. This is especially important if you sync bookmarks. In fact if you sync bookmarks, there is a possibility bookmarks may be duplicated or corrupted, so it would be a prudent precaution to manually backup your bookmarks before the upgrade. You may wish to follow these instructions for Firefox (Desktop): Manual backup of bookmarks

You may even consider doing similar backups maybe every couple of weeks if you have important bookmarks and the listing changes frequently. Also bear in mind that the new Sync only merges bookmarks - after syncing, all devices will have the same bookmarks. You have no option to sync unidirectionally from a Phone to a Desktop

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.

However, the legacy Sync protocol code inside Firefox is no longer maintained, and we plan to begin its removal in 2016. 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. (The current technical guide is here: Run your own Sync-1.5 Server)

What if I'm using another browser (e.g. SeaMonkey, Pale Moon, ...)?

Your browser vendor may already provide alternate hosting. If not, you should consider hosting your own server to ensure uninterrupted functionality.

I'm not ready to transition to Firefox Accounts-based Sync. How do I turn off the notification?

Unlink Sync from your browser to turn off the notification without upgrading to the new Sync. Once you do this, you will no longer be able to use the old Firefox Sync (version 1.1). If you want to use Firefox Sync in the future, you must sign up for an account and use the new version of Sync.

1. Click on the menu button The image "new fx menu" does not exist., followed by OptionsPreferences.
2. Click the Sync panel, then Unlink Sync.