I updated the bookmarks on my Firefox account Bookmarks Toolbar (putting them in new folders)- on my laptop and it sync'd to my phone and desktop. All good.
But now it's gone a bit crazy and I have duplicated folders on the Bookmarks Toolbar on my desktop. I delete the duplicates and it's fine for a day or so and then it does it again. I now have three duplicates of each folder on my desktop taskbar.
If you use Sync then best is to disconnect Sync temporarily during troubleshooting.
This could be a problem with the places.sqlite and favicons.sqlite files in the Firefox profile folder.
- use the "Places Database" -> "Verify Integrity" button on the "Help -> More Troubleshooting Information" (about:support) page
If errors are reported with "Verify Integrity", close and restart Firefox or reboot and retry.
If "Verify Integrity" cannot repair places.sqlite, rename/remove all places.sqlite and favicons.sqlite files in the Firefox profile folder with Firefox closed. Firefox will rebuild places.sqlite and restore the bookmarks 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
- you lose the history when a new places.sqlite is created
You may have to restore an older bookmarks backup in the bookmarkbackups folder via the Bookmarks Manager (Library).
- Bookmarks -> Show All Bookmarks -> Import & Backup -> Restore
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 (Root directory).
- Help -> More Troubleshooting Information -> Profile Folder/Directory:
Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder