Do you have any backups in your bookmarkbackups folder.

http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

jscher2000 has a tool on his website to extract out your bookmarks and save them to an HTML-format bookmark export file. If you want to try it, here is the page:

https://www.jeffersonscher.com/res/bookbackreader.html

To open the bookmarkbackups folder in Finder, use the "Open in Finder" button in the first table on the Troubleshooting Information page, and double-click into bookmarkbackups where you should see several dated files. From there you can drag and drop onto the conversion tool.

To import the HTML file, see the steps in this article: Import Bookmarks from an HTML file.

The link you gave me contained advice I'd already told you I'd done (deleting and/or renaming files in the profile folder), and did not address the issue of no new Bookmarks or History being allowed. Your response was entirely unhelpful in every sense of the word.

Have you already shut down and restarted Windows 7 to release any file locks and complete any pending updates?

Usually having Firefox create a new places.sqlite file in your existing profile resolves the issue. In one case, a user created a completely new profile and then copied that profile's places.sqlite database into the problem profile as a workaround. If you want to test a new profile:

New Profile Test

This takes about 3 minutes, plus the time to test bookmarks/history on a few sites.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like March2019, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system so we can get a clean test.

Can you save bookmarks/history in the new profile?

When you are done with the experiment, open the about:profiles page again.

To prepare to copy places.sqlite from this profile to your regular one, find the Root Directory row for the new profile and click the Open Folder button. Similarly, you can open your regular profile folder from this page. Then set your regular profile back to default.

Before copying places.sqlite, exit Firefox and allow it to reconcile the related journaling files (-shm and -wal) into the main file.

Then after all of that, when you start Firefox, it should return to your regular profile with the new places.sqlite database.

Any improvement?

The new profile can create bookmarks, but I can't figure out how to do the rest of your suggestion. Perhaps I'm just not getting it, would it be possible to simplify it further? Unfortunately I did not inherit either of my parents' computer skills. I can open the folders, but I see no way to copy anything anywhere. I can open the folders, as a I said, and switch which one is default, but that seems to be it. What am I missing? And how stupid should I feel about not seeing it?

Hi ArkleScribe, I guess try it this way:

In the March2019 profile folder, right-click places.sqlite and click Copy on the context menu

In the default profile folder, right-click a blank area and Paste

Windows should say there is already a places.sqlite file there, and what do you want to do about it? Tell Windows you want to replace the one there with the one you are copying in.

Okay, done. And nothing happened. Still can't make new bookmarks or access any old ones, and History doesn't work. :(

Did it work in the new profile, but when you copy/pasted the working places.sqlite file from the new profile to the old profile, it doesn't work in the old profile?

In that case, the problem might be with the favicons.sqlite file which stores site icons for bookmarks (and maybe for history, I don't know about that).

It seems to have worked. Won't bring back all the bookmarks I lost, but it's better than not having them at all.

Are you able to recover more bookmarks using the Restore feature and previous backups?

See: Restore bookmarks from backup or move them to another computer

Each entry on the menu should list the number of items (bookmarks+folders) in the file.

Huh. DIdn't work all the other times but this time it did. Well, I'm not gonna complain. Be confused, but not complain.

For the record, places.sqlite : History and Bookmarks.