The best session manager! Everything what's needed!

Regarding bugs and session db losses during FFox updates - this is FFox bug, not the addon's. The only cure is - make backups of sessions and addon settings (via export), also is good to switch to manual FFox update and backuping whole profile before update.

Works great! Would love the option to merge windows when restoring sessions =)

Till Now, I had no problems, but today, 13 July 2019, this extension seems to have some problems with syncronisation of SOME tabs. Indeed, some of my tabs cannot be loaded and I cannot see what was in these tabs since they are empty now. Please correct these bugs, maybe due to a Firefox update. Thanks in advance. Eric from France.
UPDATE, 15 July 2019 : PROBLEM SOLVED, THANKS !

Supernützliches Addon.
HINWEIS: Wenn das Addon nicht funktioniert, wenn es nicht speichert:
Geht in die EInstellungen des Addons (über ADDON) und löscht alle Sitzungen. Danach funktioniert es wieder.

NOTE: If Addon not works or not Save Sessions:
Go to Settings of Addon (over Firefox ADDON Menu) and delete old Session Manger Sessions. After this, Addon works normaly

Спасибо, отлично работает.
Также спасибо за поддержку Tree style tabs.

Super flexible, a must-have.