Originaly I would had given it five stars.
Sadly I've recently lost multiple sessions. SInce then, I lost all trust I had on its reliability so two stars it is.

Absolutely excellent. Has every feature I need and more, and I never use firefox without it.

Clean and powerful.

when I save one session it removes the one I saved previously. exporting sessions stopped working because of some error with website name characters or something. useless. could be suspended tabs issue. doesn't get updated ever. bugs don't get fixed ever.
seriously remove this t from the browser. it's outdated and not being updated. crashes after few uses and you can't fix it there are no easy workarounds. why keeping this useless extension in browser

Great Addon but since I installed the SIMPLE TAB GROUPS (STG) extension, it conflicts with it, and causes errors to my Firefox. Please fix that problem.

As others already said: it's completely useless. Autosave is silently failing, restoring manually saved session is practically impossible (at best you can reopen individual tabs) and it may randomly wipe your entire history of saved sessions. Then under Wayland desktop session even button to manually save a session disappeared and shortcuts do not work. The only way to do anything was opening it as tab where button came back. Also, "export sessions" button does nothing.

Newest update broke keyboard shortcuts.....

"Once again, opening saved sessions doesn't work. Only individual tabs can be opened from a saved list. Even reinstalling the addon and exporting the sessions beforehand doesn't help. It seems that somewhere indexing is set incorrectly, or due to inaccurate identifiers, the addon cannot correctly read in which order the tabs should be opened and in which window, which is causing this problem. It would be great if this could be fixed!

Tab Session Manager has been a lifesaver, as Firefox's inbuilt Restore Session frequently doesn't restore all the tabs from the last session and puts tabs in wrong containers - TSM does this all perfectly. One annoyance - tabs restored with TSM seem to display the tab tooltip only once when hovering over a tab. There is no tooltip when hovering over the tab a second time. (I'm using Tree Style Tabs).
Update: discovered that tooltips always appear over over tabs that are in a container, but only once over tabs not in a container.

Nice but why is there nowhere in the settings stated (or a "switch-account") to which account I'm syncing? I can find out so it's not a huge problem, but it's also not a huge problem I think to just implement a mentioning somewhere in the settings ¯\_ (ツ)_/¯

If you're losing your previous sessions or you want better tab management, then this extension is exactly for you.

I can't import my tabs from Session Buddy, I get "Read failed" every time I try. Tired to save and import individual sessions to see if it will work, still not importing.

Tab Session Manager was my session manager of choice until I realized that it was at fault for a very annoying problem I was having.

I still use Windows 10 on my main computer and I run many multiple desktops. Sometimes up to twelve.

With TSM active, every time I restarted Firefox, all of its (many, many) windows—which had been distributed across multiple desktops—would open on a single desktop, leaving me with several minutes of work to reorganize them into something coherent.

As well, browser windows that I'd long since closed were also opening, adding to the clutter.

Eventually this became too annoying and I started probing into the cause. Disabling TSM immediately made the issue go away so I left it disabled and started using Tab Stash, which I don't like as much but when I restart FF all the windows stay where I had them.

I'd go back to TSM in a second if I knew the multiple desktop issue had been sorted.

Worked great for years until after a recent update, it deleted all my saved sessions. On another device, not only are my saved sessions gone, but it now keeps saving every single browsing session on its own?

Just restored 19 Sidebery tabs in perfect organization after an Alt F4 to the wrong windows! EXCELLENT extension for fixing the tab restoration issue with multiple browser windows open!

It opens tabs slower than native Firefox session. And when I switched it off to try working without it, all the tabs except "New Tab"s disappeared. What is the use of "session manager" if it just loses your session?

if you throw donation prompts in peoples faces, they arent gonna like you

Has stopped saving sessions automatically; must do so manually. Only sometimes registers when a window is closed and saves then.

EDIT: deleting any re-uploaded sessions seems to allow the extension to automatically save again.