Good morning. What happens when you try to backup or export your bookmarks? You could use the latest file from the folder bookmarkbackups in your profile or the places.sqlite file.

https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_what-information-is-stored-in-my-profile https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

I suggest you backup your profile folder. Sync isn't a backup service.

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

If you use Sync, 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 -> Manage Bookmarks -> Import & Backup -> Restore
• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them

See also:

• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional
• https://support.mozilla.org/en-US/kb/cant-add-change-or-save-bookmarks

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
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Good morning. What happens when you try to backup or export your bookmarks? You could use the latest file from the folder bookmarkbackups in your profile or the places.sqlite file. Hello Terry, thank you very much for your reply. I already tried to follow cor-el's advice and I used the latest automatic backup. When I try to backup or export my bookmarks, nothing happens when I click these buttons. That was the issue I mentioned in my request. Now I 'repaired' the bookmarks in the laptop manually.... Thanks again, Ed

Good morning. What happens when you try to backup or export your bookmarks? You could use the latest file from the folder bookmarkbackups in your profile or the places.sqlite file.

   Hello Terry, thank you very much for your reply. I already tried to follow cor-el's advice and I used the latest automatic backup. 
   When I try to backup or export my bookmarks, nothing happens when I click these buttons. That was the issue I mentioned in my request. Now I 'repaired' the bookmarks in the laptop manually....
   Thanks again, 
   Ed