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How do I sync multiple accounts on one computer?

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Similar to previous question https://support.mozilla.org/en-US/questions/1091574 I have several user accounts on one PC (Win7) that I would like to sync across to the Win 10 installation on the same PC, and maybe to other devices in the future. I have this for my own system, but when I try this for another account I get an error "There is another account on the PC - do you want to merge accounts" - see attached screenshot. Of course I do not want to merge data.

The "solution" in the referenced question above suggests renaming the computer for each Sync account. Where and how do I do this? The question about merging accounts comes before I have a chance to enter Sync settings, such as the device name.

Similar to previous question https://support.mozilla.org/en-US/questions/1091574 I have several user accounts on one PC (Win7) that I would like to sync across to the Win 10 installation on the same PC, and maybe to other devices in the future. I have this for my own system, but when I try this for another account I get an error "There is another account on the PC - do you want to merge accounts" - see attached screenshot. Of course I do not want to merge data. The "solution" in the referenced question above suggests renaming the computer for each Sync account. Where and how do I do this? The question about merging accounts comes before I have a chance to enter Sync settings, such as the device name.

All Replies (3)

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Please explain what you goal with a little more detail.

And please re-submit that screenshot image, it didn't get attached to your posting.

See this support article. How do I create a screenshot of my problem? It is best to use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed a maximum file size of approx 1 MB.

Then use the Browse .... button below the Post a Reply text box to upload the screenshot.

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I have one desktop, with dual boot Win7 & Win10. Each OS has the same selection of user logins - one for each family member.

I would like to sync each persons FF data between their Win7 & Win10 logins.

I have this for my login, fine. When I tried for another login I get the message shown, suggesting that FF will merge my data with the new account. I do not want to merge data, but have several different Sync's running in parallel.

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"When I tried for another login I get the message shown, ..." Sorry, I don't understand what you are saying.

1. Each user needs their own Sync account. 2. As long as each person using that PC have their own Windows LUA (Logon User Account) data won't be merged with any other person's data. Firefox has a separate Profile for each LUA. (/user/AppData/ folder sets) 3. As of Firefox 42.0 Sync started keeping track of each device that is connected to the Sync account. You need to edit the "Device Name" a bit (maybe OS version?) to make the "names" different. See the screenshot and notice the Change Device Name button 4. That "merge" message is due to another 'device' being added to that Sync account. The assumption is that there is data already on that other 'device' and it telling you that data will 'merge'; the user has no "direction control" of Sync. There is no 'master' / 'slave' control, it always does a merge of data. And if you have no data on the "new device" there would be nothing to 'merge' with data already present on the Sync server.

Your intended use with two Windows OS's is a bit unusual, the 'norm' would be dual boot with Windows and Linux OS's. And IMO, the Sync developers didn't even take dual-boot in to mind when they created the "messages" in Firefox for Sync. I think the assumption is that a user who does a dual-boot has enough 'knowledge' to get it accomplished without 'special' messages for edge-case uses as with dual-boot systems.

Overall, what you want to do - does work! You just need to be careful when setting it up that all the Sync accounts get 'connected' properly to the corresponding LUA on each OS.

One suggestion - backup all those Profiles Just-in Case something goes wrong.


I have done similar in the past myself, but I did it with different 2 Sync accounts on the same PC in WinXP using the same LUA for the purpose of running 4 different versions of Firefox for testing the pre-release versions of Firefox. With one Sync account for each of Release, Beta, Aurora/DE, & Nightly versions. And the 2nd account was just for Release and Beta. All it took was 6 different Firefox Profiles and making sure I had each configured correctly. I did make a mistake and trashed the 2nd Sync account, twice, due to an oversight on my part; but I did get it working correctly after correcting that 'oversight'.