I had to find a replacement for the old Session Manager, which worked well until FF57, and then not at all.
I give kudos to the author of this add on for going to the trouble to provide an extension that substitutes for the legacy Session Manager in part. If it can duplicate more of the functionality of the older extension, it would rate FIVE stars for sure. But I thank the author and rate four stars at this time.
There are issues which I hope can be dealt with as this extension develops:
- I had a large 196 tab session saved, which Tab Session Manager shows OK, but when I try to open the session, only a portion of them do load. There seems to be a limit here. It would be nice if there was not.
- I note the latest version 1.5 has an option to Export the tabs (I presume as a list of links), but I haven't located this feature. This would enable me to sort through the 196 tabs mentioned in the previous point, so I hope I can find it - FOUND IT! Cool. Oh, but it only exports as a .json file which is not so useful. Update: but it is not to hard to manipulate the file with Notepad++ using "windowId": value to extract the tabs from a particular session.
- I echo the statement of "Anonymous user 8e0130" who asked "Is there anyway to have it not load non-active tabs?"
----------------------------

There's still a lot of work to do... but just to be able to import and open my old session manager's sessions (under ubuntu find them under ~/.mozilla/firefox/*some cryptic-key*.default/sessions/*here they are!!!*, which I though I'd never see again under firefox 57+, has just made me sooooo happy!!! So I just wanted to say THANKS!!!! a) For my sessions back, b) for giving us an alternative to keep going.

And don't listen to all those stupid comments of people, who probably think, open-source code just falls down from trees or something...

ウインドウのサイズ ページの表示位置 を保存できるように あれと寸分違わない機能が欲しい

It’s almost there just needs four things

First the ability to sort sessions alphabetically.

Second ask for conformation when deleting a session (one miss click and it could be gone that’s not good).

Third don’t activate every window when opening a session, only open the link when the user clicks the tab.

Forth when you open the tab manger window it should default to whatever view the user had last. So if the user last had “User Saved” clicked and it was set to sort by oldest it should stay like that every time you open the window until it is changed (even after closing and reopening Firefox). Or at the very lest you should be able to set the default view in the settings.

The Firefox community is counting on you plz i created an account just to write this.

Very simple and easy to use. Found a work around for not supporting the import of Session Manager files, but I really appreciate that they can now be imported.
I would like the option to automatically load the last session when Firefox is started. Otherwise I can't think of anything else I need from this addon.

As others have said, there is a bug when restoring sessions, it doesn't restore all windows or tabs. As this is the only functionality of this add on I can't give more than 1 star.

Edit - The latest update has fixed the issue above and also added lazy load.

TSM is getting better as far as readibility goes.
Thanks for the changes, but please, add the ability for the user to set a still better readability choosing fonts parameters and colors.
Low contrast colors are a pain in the ... eyes, especially for people with "light sensibility"
;-)

使わせていただいています
黒系のテーマ時、文字色が見づらいので、背景と同化しないような文字色を選べたら良いなと思います

Do what i want from a session saver but i remove one star because it load all the page when i restor a session. It would be nice to just repopulate tabs and load only when user check on them. There's a little problem with the link in the "tab session manager" 's page under information menu too. The link to the addon point to the japanese page instead of the system language.

Thanks for your efforts. They are appreciated.
But I would like very much to see any opened user saved session automatically saved (like every minute or so), under the same title we initially gave to the session. Your latest update is not doing this.

You should give option to save sessions file to different folder as a backup just in case.
also, you need to add more settings.

Simply great work. but if I remove a session, the view does not refresh automatically so it looks wired sometime.

Extension is exactly what I was looking for - simple and single functionality of saving sessions. But it does not remember the options set. I have disabled autosave, still it keeps saving the sessions.

I thought I would try this to replace Session Manager, which will likely not work with FF 57. I disabled SM and installed this, saving my session with the toolbar button. When I restarted FF, I only see one tab, which happens to be the first tab in my session. (It's also a pinned tab, if it matters.) The session displayed in the toolbar dropdown has all of my previous tabs, so I'm not sure what's wrong. I did disable the tree-related option in the settings. (I'm using FF 56 still.) Lot of potential here, though!

Update: When I tried loading a session several days later (including after a restart of FF), it did indeed work.

I really like this add-on because I can use it on FF57+ and it's compatible with Tree Style Tabs.
I have to say though currently I find myself rarely really using it besides for saving the one session that i have every few minutes.
Main reason for that is the restore behavior. Like someone else already mentioned, when you restore a session it opens a new window and loads every single tab of the session.
Loading as in actually opening and displaying each webpage.
It would be much better to have it open the tabs "unloaded" like when you initially start FF.

Next thing would be a few more options and functionalities.
- Prompt me for a session to load on start.
- Make sessions more like dynamic savestates, so i can overwrite them. E.g. I have a session 'General'. When I load that the manager should "know" that the session is loaded and later when the window is closed or the session saved it should save the changes that were made during the session was loaded into that same session state.
Right now you can only save a new session with same name but different timestamp.
- Give option to only save current window or a selection of windows to a specified session. So one can work with multiple sessions at the same time.
- Give option to load session to current window or open in new window / attach to current session or open as independently loaded session.
- use standard UI font
- introduce groups
- save and restore per tab history

With all of this it would be perfect (and basically a clone of legacy add-on "Session Manager")
I know it's a lot to ask and some things aren't even possible yet due to Mozilla not releasing the needed API.

Right at the time I was looking for a replacement for OneTab this beauty appears. Thank you very much.

yesterday i had a closer look to TSM and got a clue how it works and what features.

i also had tab-saver installed and dismissed it now.

but what i miss is an import export feature like tab-saver. maybe not for separate sessions but for all sessions would be nice.

another point to mention is the UI design - i would prefer it more clear, eg:

1 Window, 1 Tab | Open | Delete
(2017-10-19 11-12-13)
Window1
(fav)(tab)

i had a closer look into and that is possible when positioning the div elements in another formation. ofc the css need a polish to fit again.

translating may be more complicated because many strings are hard coded and some are only notify(e.message);

PS @Jacob - running perfect on b9 and now b10 - new window all stored tabs. try a new profile

4* because import/export ;)

a proudfull replacement for legacy "session manager" - wonderful job.

Works really well, but adding an option to automatically restore a session when booting up firefox would be great. I like to keep outlook and slack as pinned tabs that start up with firefox, but get rid of every other tab when I close firefox.

This extension is really nice! Thanks for making it happen! I'm on FF 57 beta right now and session management is pretty messed up. Without this extension I will lose my tabs every time I restart FF.

I found one problem: this extension would save and reopen private windows as well, which defeats the purpose of a private window. I hope there's a way to filter them out of the save, or at least out of the autosave.

A feature request: Is it possible to add a "remove all" button? Remove them one by one can be a pain at times.