If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers/profiles before using sync again.

[v57+] Places Maintenance is built into Firefox.

Type about:support<enter> in the address bar.

You will find Places Database near the bottom. Press the Verify Integrity button.

When done, copy and post the results here.

https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

Thanks FredMcD. I have gone through the steps, but am not clear where or how to post the results to the page reference given.

Does the report show a problem?

The places.sqlite file contains your History and Bookmarks. And it looks like it is corrupted.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox. The browser should then create a new place.sqlite and recover your bookmarks from the backup files.

Note: Your history is not backed up and will be lost.

This only works for a short while. After I reopen Firefox, I delete the unwanted bookmarks in the top ribbon. Close and reopen Firefox. Then somewhere between 5 and 5 1/2 minutes later, with no other activity or action, they all come back. I have gone through the process twice to be sure.

Here is the Places Integrity data that I could not post earlier: > Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: invalidateCaches + The caches have been invalidated > Task: checkCoherence + The database is coherent > Task: expire + Database cleaned up > Task: originFrecencyStats + Recalculated origin frecency stats > Task: vacuum + Initial database size is 5120KiB + The database has been vacuumed + Final database size is 5120KiB > Task: stats + Places.sqlite size is 5120KiB + Favicons.sqlite size is 24320KiB + pragma_user_version is 54 + pragma_page_size is 32768 + pragma_cache_size is -2048 + pragma_journal_mode is wal + pragma_synchronous is 1 + History can store a maximum of 42033 unique pages + Table moz_origins has 631 records + Table moz_places has 810 records + Table moz_historyvisits has 13 records + Table moz_inputhistory has 0 records + Table moz_bookmarks has 1150 records + Table moz_bookmarks_deleted has 0 records + Table moz_keywords has 0 records + Table sqlite_sequence has 0 records + Table moz_anno_attributes has 1 records + Table moz_annos has 13 records + Table moz_items_annos has 0 records + Table moz_meta has 4 records + Table sqlite_stat1 has 15 records + Index sqlite_autoindex_moz_origins_1 + Index sqlite_autoindex_moz_inputhistory_1 + Index sqlite_autoindex_moz_bookmarks_deleted_1 + Index sqlite_autoindex_moz_keywords_1 + Index sqlite_autoindex_moz_anno_attributes_1 + Index moz_places_url_hashindex + Index moz_places_hostindex + Index moz_places_visitcount + Index moz_places_frecencyindex + Index moz_places_lastvisitdateindex + Index moz_places_guid_uniqueindex + Index moz_places_originidindex + Index moz_historyvisits_placedateindex + Index moz_historyvisits_fromindex + Index moz_historyvisits_dateindex + Index moz_bookmarks_itemindex + Index moz_bookmarks_parentindex + Index moz_bookmarks_itemlastmodifiedindex + Index moz_bookmarks_dateaddedindex + Index moz_bookmarks_guid_uniqueindex + Index moz_keywords_placepostdata_uniqueindex + Index moz_annos_placeattributeindex + Index moz_items_annos_itemattributeindex > Task: _refreshUI

Can you confirm whether you are using Sync to sync the bookmarks ?

If you have the iCloud Bookmarks extension then uninstall this extension.

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 a 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

See also:

• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file
• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> 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

I disabled the iCloud Bookmarks extension. That seems to have been the cause of the problem.

I deleted the "places" files, but not the "favicons" files.

The links to the other help information were most useful. Thank you all for your help.