Sync uploads data from all connected devices to the Sync server and merges this data to all connected devices, so all devices get the same data eventually. All connected devices have the same status and it is not possible to set a specific device as the master.

You can consider to export the bookmarks to an HTML file and import the bookmarks on the other devices or restore a JSON backup if you do not need to preserve the current bookmarks.

• https://support.mozilla.org/kb/restore-bookmarks-from-backup-or-move-them
• http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox

on the menu bar, it looks like Bookmarks has copied all the folders multiple times, so instead of 9 folders in there, theres about 150. How do I delete all the unwanted duplicated items without having to do it one at a time.

I tried selecting all (control A) and deleting but it causes Firefox to crash. I tried selecting a few at a time, again it crashes. Even deleting one at a time takes about a min per folder

Try this extension:

• Bookmark Deduplicator: https://addons.mozilla.org/firefox/addon/bookmark-deduplicator/

You can check for problems with the places.sqlite database file (bookmarks, history) in the Firefox profile folder.

• Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

ok there is something seriously wrong with Firefox.

Yesterday, I tried using the add ons, the first scan showed 172 duplicates which I deleted. I scanned again and it found over 350. After deleting the third scan found over 700, which I deleted.

The folders in the bookmarks in the top menu showed over 350 folders. I tried deleting one at a time, which was very time consuming and would cause FireFox to intermittently freeze. I tried deleting the folders in groups, each time it caused Firefox to freeze and then crash. I tried selecting all and deleting which cause the same freeze and then crash. After getting completely frustrated, I gave up.

So I come back today, Firefox is running extremely slow. Now there are over 1500 folders in Bookmarks. I havent done anything since yesterday, no other computers were running or anything.

If this helps. I am running Windows 10 and all other apps work just fine.

Disconnect each device from Sync when running Places Maintenance or using Bookmark Deduplicator. Keep each device disconnected until all devices have been fixed. Once they are all fixed change your Firefox Account password to clear your data from the Sync server. Then reconnect your devices one at a time. Doing otherwise might just cause the issue to recreate itself as your devices poll the Sync server looking for data changes.

I have this one machine on, nothing else is on. I disconnected it from Sync and reset my password. I tried deleting 1500+ folders, which actually seemed to work. However, it kept adding a website. I would delete it and it would just come right back, sometimes once most of the time about 5 times. I closed and reopened firefox and all the folders were again back in bookmarks, with Firefox barely able to run.

You can check for problems with the places.sqlite database file (bookmarks, history) in the Firefox profile folder.

• Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/

If the Places Maintenance extension can't repair the places.sqlite database file then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database file from the most recent JSON backup in the bookmarkbackups folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

You may have to restore and older JSON backup manually if the most recent backup is already corrupted.

Didnt work

So I uninstalled FireFox. I went in and deleted the app data file. I went into the registry and deleted the Mozilla file as well

I reinstalled Firefox and it worked fine till I went into sync and signed in. At that point, Firefox froze. After closing through Task Manager, it continued to freeze. I finally got it to open and watched it add the folders back into the bookmarks bar. It also created the 120+ folders in the Bookmarks Menu bar.