If you've run into a problem with Firefox Sync, this article will walk you though the most common solutions.

Error While Syncing

There are number of things that can cause this:

• Your Sync client isn't compatible with the data you have on the Sync server. See I upgraded something and now Sync doesn't work
• Your password is incorrect. See How do I change my password?
• Your Sync Key is incorrect. See Sync your Firefox bookmarks, history, passwords and more
• If you've set a master password and haven't unlocked it
• The Sync servers are under a heavy load - in this case, the error will stop when the server load returns to normal.

I upgraded something and now Sync doesn't work

We recently changed a lot of things about how Sync works. One of those was the way it stores your information. If you've updated one of your devices to Firefox 4 Beta 8, Firefox 4 B3 for mobile, or the Sync extension to version 1.6, your Sync data has been updated to the new format. This means that any of your other devices which have not been updated, will need to be updated in order to keep syncing.

• Firefox Sync add-on page (for Firefox 3.5 - 3.6)
• Firefox 4 Beta
• Firefox 4 Beta for mobile

Where can I find the code to add a device to Firefox Sync?

Where can I find the code to add a device to Firefox Sync? shows you how to find the code on a mobile device, an iPhone and another computer.

What is a Sync Key and where can I find it?

See Sync your Firefox bookmarks, history, passwords and more

I've lost my Sync Key, what can I do?

If you don't have a copy of your Sync Key saved anywhere and want to use Sync without creating a new account, you can generate a new Sync Key.

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Click on the Sync tab.
3. Click Set up Firefox Sync and a new window will open.
4. Under I already have a Firefox Sync account, click Connect
5. Click I don't have the device with me
6. Enter your account email address and password
7. Enter some characters in the Sync Key section (it doesn't matter what you enter)
8. You will see a notification that your Sync Key is wrong. Click the new link that appears - I have lost my Sync Key
   
9. A new window will open displaying a Sync Key - ignore that and click Generate
10. A new Sync Key will be made for you. Please take a moment to print it out or save it on your computer. Then click Change Sync Key
    
11. You will see the Setup Complete screen. Click FinishDone to close the setup window and take you back to the Sync panel.

How do I change my password?

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Click on the Sync tab.
3. Click the arrow next to Manage Account to reveal the Change Password link.
4. Click the Change Password link and a new password sheet will slide downwindow will open.
5. Enter your new password and then confirm it.
6. Then click Change Password.
7. Close the Settings page. Any changes you've made will automatically be saved. .