Awesome!

Very good at saving tab states, even in disastrous scenarios. However, it does not play well with "Tiled Tab Groups". While Firefox's default session save function (in the rare scenarios in which it actually functions properly) will restore with the tab groups intact, Tab Session Manager will destroy the group states, and loads them all in a single group. I'd suggest then that it simply doesn't seem to respect hidden tab statuses? That said, still the best we've got in Quantum by a mile so far.

After a year or so of not using this extension, I was very pleasantly surprised when I installed it again today. It seems a lot more stable than what I was used to.
As a Tree Style Tab user, I highly recommend this extension.

Edit: The latest update has a much clearer layout which can be opened in a separate tab. Very useful.

How to export sessions outside Firefox? Thanks!

Thanks for pointing out the Firefox bug that prevents add-ons from running by incorrectly flagging them. I love the Tab Session Manager. I rock 4 windows with ~20 tabs on each at any given time. Thanks a mill!

What I wrote previously (ignore):
"Please get your add-on signed, it has been removed from Firefox's list of approved add-ons and thereby inactivated on my computer. I'd give 5 stars otherwise."

Пожалуй самое удобное и хорошо зарекомендовавшее себя расширение, пользуюсь больше года и не подводило до недавнего времени, когда количество вкладок перевалило за 400!! Теперь программа не открывает окно с выбором сохранений, сбрасывал настройки, удалял и ставил по новой.. не работает ((

From now Firefox works only with signed add-ons.
Please sign your add-on.

PS temporary solution from Firefox docs
about:config xpinstall.signatures.required = false

Works great but does NOT Support Multi-Account Container. Every time session is restored, you'll have to reopen the tabs in the desired Container which is really annoying. Otherwise, it's a great must-have add-on.