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Sync working only partially, not all data synced

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  • 1 has this problem
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  • Last reply by ale.re

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Hello, I have two laptops, an old one with a synced firefox, and a new one where I want to get all the passwords, tabs, theme, settings and extensions. The OS is the same (NixOS, Linux).

I can successfully log-in and enable sync on the new laptop: it's possible for me to see the list of tabs from the other device, open and sync those tabs, but other things are not synced or synced partially.

For example: of the 30+ passwords on the old device, only 15 are present in the new device; no theme or extension is synced, bookmarks seems to be properly synced.

I don't know where to get more info about the sync (besides the about:sync-log page, which shows no logs), so I can't really tell what's going on. Indeed, nothing changes if I press the "Sync now" button.

I also tried refreshing firefox or creating a new profile from scratch and sync that again, but to no avail. Do you have any suggestion? Thanks

Chosen solution

Are you using Firefox from the Mozilla server in both cases ? Does the old laptop run the same Firefox release version (91.0.2) or an older version (see about:support)?

All logins should be synced, but in case of issueus you can transfer logins.json and key4.db directly from the profile on old device to the profile on the new device.

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.


  • bookmarks and history: places.sqlite
  • favicons: favicons.sqlite
  • bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
  • cookies.sqlite for the Cookies
  • formhistory.sqlite for saved autocomplete Form Data
  • logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
    key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
  • cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
  • persdict.dat for words added to the spell checker dictionary
  • permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
  • sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)
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Chosen Solution

Are you using Firefox from the Mozilla server in both cases ? Does the old laptop run the same Firefox release version (91.0.2) or an older version (see about:support)?

All logins should be synced, but in case of issueus you can transfer logins.json and key4.db directly from the profile on old device to the profile on the new device.

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.


  • bookmarks and history: places.sqlite
  • favicons: favicons.sqlite
  • bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
  • cookies.sqlite for the Cookies
  • formhistory.sqlite for saved autocomplete Form Data
  • logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
    key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
  • cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
  • persdict.dat for words added to the spell checker dictionary
  • permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
  • sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Helpful?

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I'm using Firefox 91.0.1 on both devices, I think it's the most recent version on the package manager - but release notes don't seems to be related to my issues:

https://www.mozilla.org/en-US/firefox/91.0.2/releasenotes/

It's from mozilla servers in both cases, yes (archive.mozilla.org).

I copied `logins.json` and `key4.db` and got my saved passwords in the new profiles, extensions and colors are not synced so I also copied the `extensions` directory and enabled the extensions. I shared the color by simply sending the tab with the color scheme to my new device.

Thanks for your help!

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