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Which PC is the master for purposes of Sync?

  • 3 replies
  • 6 have this problem
  • Last reply by John99

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There are thousands of posts here for how to set up and troubleshoot Sync but none i can find that tell me how it actually works and how to control the sync process from a master/slave standpoint.

I have an old XP box that I'm replacing with a new Lenovo, plus a Dell XPS laptop that I'll be continuing to use. I want the laptop and the Lenovo to mirror the FF settings on the old XP desktop that I'm retiring. But the changes are flowing in all directions; things I set up on the Lenovo are populating back to the XP.

How do I flag the XP box as the master so its config will flow to the other two machines?

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Hi Geoff,

You may possibly be misunderstanding Sync. It is not intended to be a server based backup system. That may explain your difficulties in discovering instructions.

Here is a list of articles on using sync

Note that Sync is to sync between devices and not to sync from a server.

  1. You will need to sync from the XP to the other two machines.
  2. Then once you retire the XP. You will need to choose one of the other machines as the main one.

IIRC Sync is planned for deprecation and the replacement system may well allow proper server based syncing; where the server is the backup.

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<<Then once you retire the XP. You will need to choose one of the other machines as the main one. >>

How do I choose the main one? I have read many of the docs and never found a hint about this.

Setting up Sync has been very difficult. The system messages are's not even possible to know if a machine is set up unless you know the "secret" about seeing "Set Up Sync" on the menu. Might be logical to the developer but not to this end-user.

Last night I was running back and forth for hours trying to set it up on my PC's. My notes include six sets of 12-character codes and one of those long password strings. When the link-up fails, there's no error message.

Last night I renamed the whole feature "Firefox Stync" I was so frustrated. Who designed this anyway? Pardon the rant but it obviously was not tested by end-users, judging from the huge volume of questions it generates.

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Yes it may be rather, none intuitive & unclear on how Sync is intended to be used. The fact that it is penciled in for replacement rather than any further development suggests it has not been too successful.

If you read How do I set up Sync on my computer? it has a Part1 and Part2 referring to

Those are the two devices the master device that is synced from, and the secondary device for backing up or syncing to.

Starts the sync process.

Note from

You can choose how your data is synchronized when you create your Sync account and whenever you add a device. When you set up Firefox Sync, click the Sync Options button at the bottom-left corner of the setup window to select one of these options:
   Merge this computer's data with my Sync data (default; recommended)
   Replace all data on this computer with my Sync data
   Replace all other devices with this computer's data