First, don't use Firefox Sync with Xmarks (Foxmarks was the name prior to 2007). That is known to corrupt Firefox bookmarks and to produce duplicates; and in some reported cases it was dozens or many dozens - folders, too.

Inside Firefox open Help > Troubleshooting Information scroll down that internal page to Places Database and see the Verify Integrity button. Use that to fix the Places database file in your Firefox Profile folder.

Restart Firefox and see if that fixed the duplicates problem.

Beyond that, I would condemn Xmarks as the culprit.

Followed your instructions - great, but then realised that Firefox was picking up all the book marks from my Mac. Went into Preferences and unticked the box for syncing bookmakrs on all browsers and that has finally cleared them all out.

Thanks for your help

ALL bookmarks started self-replicating after Fire Fox Upgraded to Quantum. there is an add-on to delete duplicate bookmarks but it specifies it does NOT work with Quantum, only older versions of Fire fox. so, now i have way too many bookmarks+folders that are meaningless duplicates. unfortunately, i do not have days to go thru them all by hand. i have no other devices or browsers that i use so, syncing with other things is NOT the problem.

quirke21

First, you're not using Sync are you?

Probably corruption inside the file that holds the Bookmarks.

Inside Firefox open Help > Troubleshooting Information scroll down that internal page to Places Database and see the Verify Integrity button. Use that to fix the Places database file in your Firefox Profile folder.

Takes a couple of minutes to do that.

Let us know if that solves the problem.

I acvtually got this sorted some months ago following your earlier posts. Don't have any problems with Firefox. Just trying to rescue all my Thunderbird address books etc from a deceased computer without much luck. will probably have to post a question on the "Thunderbird "forum for help.

Apprec ated your follow up

the-edmeister said

quirke21 First, you're not using Sync are you? "Inside Firefox open Help > Troubleshooting Information scroll down that internal page to Places Database and see the Verify Integrity button. Use that to fix the Places database file in your Firefox Profile folder." So I do that, and get this message: > Task: checkIntegrity + The database is sane > Task: invalidateCaches + The caches have been invalidated > Task: checkCoherence + The database is coherent > Task: expire + Database cleaned up > Task: vacuum - Unable to vacuum database > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task. That's all I get, and the bookmarks are still there by the dozens. some have appeared from years and years ago...why do I have 23 AirTran bookmarks? Folders are duplicating, for one bookmark I have over 50...and more are repeating. You say I can use that to "fix the Databases place" ....no clue at all what that means..... fix what? From what I can tell, I am not using Sync, I did disconnect that some time ago. Should I just delete Firefox altogether and stick with IE or Chrome? My computer tech tells me its worthless, but it's easier that IE or Chrome for me to use. Thanks for your replies

BEST thing that fixes all of it- Download and install a Fire Fox ADD-ON EXTENSION CALLED BOOKMARKS DUPES. it looks like a double star(goldenrod over turquiose and the icon will appear in the menu bar of your browser top right. USE it to DE-duplicate your bookmarks and folders. it works perfectly. the original duplication problem went away after X-marks was discontinued.

Thanks, wasn't sure if that was a legitimate site. The other answer really made no sense to someone who isn't a tech. This seems to have worked, I am currently deleting over 4000 bookmarks when I should have maybe 100.....