After upgrading to FF 84, my previous sessions are no longer saved and restored unless I restart in Safe Mode. - I have Restore previous session checked in Preferences. - I have opened new windows and tabs and one by one disabled and restored every add-on that I have had enabled and quit and restarted each time, until every single add-on has been disabled, and still the previous sessions are not saved and restored. - I have looked in the sessionstore-backups folder with each restart, and there is never any file for the previous sessions in it. - Again, even when there are absolutely no add-ons enabled, the previous session is not saved and not restored. - Again, only when I restart in Safe Mode is the previous session saved and restored. What is the solution?