It's probably a good idea to make a copy of those JSON files in another folder that Firefox won't prune over time.

Did you try restoring one of the 420kb backup files to your new laptop (either local backups from an earlier date, or from the older laptop via a USB flash drive)?

On either laptop, is the display in the Library dialog (Ctrl+Shift+b) any different than the bookmarks menu/sidebar?

Yes, I have already made copies of the json files on another part of the drive on both computers.

I did not try to restore anything on the new laptop, I was afraid the same thing would happen as on the old (it would just erase and not import thereby leaving me with years of bookmarks lost on both laptops.) I thought it might be a bug in the new Firefox or something.

Nope, the Library view is the same as the menus on the old laptop. Empty.

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On the new laptop, I did find some of the missing folders and links, they had been moved to another folder in a strange place. However, I have LOADS of issues with the new laptop's bookmarks. There are copies upon copies of folders and files. For example, I have multiple instances of "Bookmarks Menu". One instance had been moved to a folder inside my Bookmark Toolbar folder which was nuts. There are three or four sets of Menu Bookmarks folders in the root as well. Some folder sets have less links than other folder sets. At this time I am trying to make sense of everything and going in by hand to merge folders and compare links, erasing the duplicates, etc.

I don't know wth happened, but it's a mess in there.

I even have multiple instances of Bookmarks Toolbar.

It's like a drunk got in here and just started copying and pasting wherever they felt like it.

Rather than try to repair everything by hand, if it's not critical to preserve history, it might be easier to start with a clean database. You can rename the old one in case you want it back.

Open your current Firefox settings (AKA Firefox profile) folder using

Help > Troubleshooting Information > "Show Folder" button

Switch back to Firefox and Exit

Pause while Firefox finishes its cleanup, then rename places.sqlite to something like places_sqlite.old

In the bookmarkbackups folder, move or rename the "bad" backups so that the newest JSON file is a good one.

Restart Firefox. Upon restart, Firefox will create a new places database and restore the last backup it finds. Any luck?

Ok thank you, I will give that a try and see what happens. I went ahead and re-organized, by hand, what I had on my new computer. I backed that up in json and html for safekeeping. Will try what you suggested on my old computer today, I have nothing to lose on that one :)

I'll check in with you later :)

cor-el posted a suggestion in another thread that might work for you depending on your Windows version on your old PC: https://support.mozilla.org/en-US/questions/954375#answer-420280 (Previous Versions tab)