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I have two computers synced. How does Firefox know which one is the master device?

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  • 3 have this problem
  • Last reply by cor-el

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I updated Firefox to version 55.0.2 yesterday. After restarting I lost all the data in the browser bookmarks, the session and also it logged me out of the sync. After logging in it started syncing but it didn't sync the bookmarks. I decided to restore the system, but after doing so although the session was back all the other data was not there. I synced again and bookmarks didn't sync. Finally after logging out and in again I managed to get the bookmarks back. However I noticed that it was a problem with a plugin which caused this. It was the theme that was not compatible with the new version of Firefox. So now I have the old theme on my laptop, and different one on my desktop. Both computers are synced but the theme is different on my desktop. My question is: How does Firefox know which device is the master device? If i remove a plugin let's say FlashBlock on one machine, it gets removed on the other machine. What if i lost all my data from the browser and it started syncing and removing all the plugins and bookmarks thinking that i just want to remove everything, and then the other computer lost it too. Is it possible?

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There is no master device when you use Sync with multiple devices. All devices are equal and data from each computer is uploaded to the Sync server. Data on the Sync server from other devices is downloaded and is merged with data stored on this device, so eventually all devices will have data from all connected devices (there are some limits about what data is synced).

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I have the exact concern about which system is the master. If there is no master, what happens with conflicting settings. One system may have a different home page than the other (this is an EXAMPLE ONLY, to illustrate my point). Will the home page from system #1 go to system #2, or will the system #2 home page go to system #1? Regards to the community!

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Hi HopefulNeophiliac

There are special preferences that specify what settings (prefs you see on the about:config page) to sync to other devices.

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

There are services.sync.prefs.sync<pref-name> prefs with a value true for each pref that is by default included in syncing preferences. You can set the corresponding services.sync.prefs.sync.<pref-name> pref to false to prevent syncing this pref.

  • prefs that have a corresponding services.sync.prefs.sync.<pref-name> pref that is set to true will be synced to other devices
  • prefs that have a corresponding services.sync.prefs.sync.<pref-name> pref that is set to false will be excluded from syncing
  • if you want to sync prefs that are currently not included then create a corresponding Boolean sync pref and set its value to true
    • services.sync.prefs.sync.<pref-name> (omit the <>)
  • you can set the services.sync.prefs.sync.browser.startup.homepage pref to false on the about:config page to prevent syncing the home page setting