The old Firefox Sync system will be deactivated towards the end of 2015 to complete the transition to the new Firefox Sync. If you are using the old Firefox Sync, you'll be prompted with a guided tutorial to make upgrading as easy as possible.

If you're unable to follow the tutorial, follow these instructions to update manually: Sync your Firefox bookmarks, history, passwords and more.

Firefox Sync lets you access your information on all your devices. The new, Firefox Accounts-based Sync, release 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.

When will the old Sync servers be switched off?

The old Sync servers will be turned off before the end of 2015, but no firm date has been set. This decision will be based on ongoing monitoring of their use and the success of our transition strategy.

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).

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. The old Sync infrastructure will be maintained until previous ESR versions reach end-of-life on August 4.

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.

Are there any security concerns with 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 is safe from prying eyes.

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 old 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 another browser (e.g. SeaMonkey, Pale Moon, ...)?

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