Perform the suggestions mentioned in the following article:

• Latest Firefox issue

Check and tell if its working.

Also, Update All your Firefox Plugins -> https://www.mozilla.org/en-US/plugincheck/

• When Downloading Plugins Update setup files, Remove Checkmark from Downloading other Optional Softwares with your Plugins (e.g. Toolbars, McAfee, Google Chrome, etc.)

useless response....

A possible cause is a problem with the file places.sqlite that stores the bookmarks and the history.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_places-database-file

See also:

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions

• https://support.mozilla.org/kb/common-questions-after-updating-firefox

cor-el,

This turned out to be the root cause for my problem. Simply renamed the places.sqlite.corrupt file to places.sqlite and my profile (including bookmarks) worked again. Thanks!

By the way, I first noticed that something was wrong with my _profile_ when, in addition to lost bookmarks, I noticed that I couldn't create _new_ bookmarks. Also was not able to restore bookmarks from a backup .json file. So I created a new profile, and was able to restore the bookmarks from the original profile's backup. That led me to exploring your suggestion. Thanks again!