Are you using sync?

yes - to coordinate my home and work computers (and my devices)

If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers before using sync again.

But how do I fix the problem? If shutting down sync fixes the problem, then wouldn't the problem just resume once I turn it back on? Does this happen with anyone using sync?

FredMcD said

. . . .perform the same repair on all computers before using sync again.

Meaning, run all of your Firefox programs, remove the empty folders from each. After you are sure all is done, start Sync again.

I have this same problem--- and the question has not yet been answered--

have at least 50 empty "Bookmarks Toolbar" folders - I can delete them one by one but they just appear again. This doesn't affect my actual bookmarks, but it's annoying and the list is getting so long its hard to see my actual bookmarks above them. How can I i) delete these ghost bookmarks toolbar folders in bulk; and ii) redo my settings so this stops happening?

How to fix this?

If you are using sync, try doing all of the above.

I only have Firefox on my home Computor, not syncing to any other devices and I have this problem. How to stop all the empty bookmark folders in this scenario??

Thank you for any assist

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

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

See also:

• http://kb.mozillazine.org/Locked_or_damaged_places.sqlite
• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

If you use Sync then best is to disconnect Sync while performing maintenance/repair efforts to files in the Firefox profile folder.

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

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox