It is exactly as explained in here but for Debian Buster : https://bugzilla.mozilla.org/show_bug.cgi?id=566212

Closing Firefox by shutting down Debian makes session be restored First of all, I set: on Firefox start, open start page, about:home as the start page and session to be restored after a crash.

If I have Firefox opened (visiting many sites in many tabs), but instead of closing Firefox directly, I shut down Debian Buster, when I start Debian and open Firefox, the session is restored with all those sites and all those tabs.

Reproducible: Always

Steps to Reproduce: 1. set on Firefox start, open start page 2. set about:home as the start page 3. set session to be restored after a crash 4. open 2 tabs 5. go to 2 sites (1 site in each tab), but don't close the 2 tabs 6. click the button on top-right corner to shut down / turn off 7. select Shut Down / Turn Off 8. start Debian 9. open Firefox Actual Results: The 2 tabs with the 2 sites are opened automatically.

Expected Results: Firefox opens about:home.

Can I add (somewhere, where?) a command line to be executed before shutdown in order to close properly Firefox?

However, as most of the time, if I shutdown my computer with Firefox still being open . . . .

You should Never shut down the computer when programs are running. Programs need to properly shut down so that any open files are properly closed. If not, the files can be corrupted.

Sorry, but as a human being, I found this answer invalid and unacceptable. It sounds like we must do an action as we had to answer an order from a computer, as, if I may push the logic to the end, if human had to be slave of computers. When a user push the shutdown button of any Gnu/Linux OS, MacOS or ... Firefox should be able to handle how to quit properly by itself, not expecting the user to quit the way it itself desire.

By the way, I have never experimented this problem neither on windows (17 years ago) neither Mac OS (15 years ago) neither Ubuntu (during the last 10 years), only since I switched to Debian. Maybe some collaboration with Debian needs to be done... After some research, it seems that this bug is known for 14 years in here : https://bugzilla.mozilla.org/show_bug.cgi?id=336193

Would a gnome extension creating a "close Firefox and shutdown button" work ? What would be the command? quit Firefox && sleep 5 && shutdown - h now? I don't know how to "quit" properly Firefox with a command line...

You may need to submit that Crash Report to the Mozilla Crash Reports system manually, by clicking on that report number to submit it. A "submitted report" would start with a BP- prefix in most cases, that is the type of report that "we" can view; although some without that BP- have been able to be read by some support contributors, but I have never been that lucky - or maybe I don't know the "trick" to view them unless the BP- appears.

But I agree with FredMcD, a proper shut down of Firefox is best to reduce the chance of user data being lost - for as long as I have been using Firefox (starting in Aug 2002 with Phoenix 0.4).

But a proper shut down should happen automatically when the session is closing. We are talking about computers that are supposed to do automatic tasks...

A ShutDown error means something about Firefox is not closing properly.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh).

Don't do anything. After a few minutes, close Firefox. Is the problem still there?

I I close/quit Firefox by clicking on the "quit" button in the UX interface, I never experiment any problem. The issue happen only when, after working, I simply click on the shutdown/switchoff computer button without closing/quitting gracefully Firefox before... It looks like Debian and Firefox aren't able to understand each other about the action shutdown. Ubuntu and Firefox is OK. Debian and all other software are OK Only the couple Debian/Firefox seems to have difficulty to collaborate on this action.

Well, if I type in the terminal the command "killall firefox-esr" it does the same. Firefox doesn't seems to like being "killed" so the big wonder is how to tell Firefox to quit itself if we can't quit it from outside...

That is what is asked there for 14 years : https://bugzilla.mozilla.org/show_bug.cgi?id=336193 I'm far from being the first and alone person to face this issue and wondering how to solve it.

Why are you ignoring my suggestion about submitting that crash report ID to Mozilla, and then posting the resultant hyperlink which would allow someone here to see and read your crash report?

https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support

Well, I don't get any crash report only the screen saying the session couldn't be restored automatically, do you want to restore it? or something like that (it's not in english so I'm translating what is says).

By the way, yes, I shut down well by clicking on the system shutdown function, I do not do this by a long press on the power button.

I did not get that behavior under Ubuntu, only since I migrated to Debian 10 but I experience it on 2 computers under Debian 10.

True, "quitting Firefox properly" is not difficult but why should we make an exception for Firefox and bow to its need. Firefox should know how to quit properly on its own when the operating system gives it the order because it has itself received the order to shut down. All other applications and services can do this under Debian. Why not Firefox?

I am surprised at the lack of expectation and the acceptance of such a simple fault on the part of the community. I always used Firefox, I always defended Firefox. I expect excellence from it. This defect is not serious indeed but it's not excellence. This bug is known for 14 years, before Firefox reached version 2.0 even. https://bugzilla.mozilla.org/show_bug.cgi?id=336193 After all these years it still is only Priority: P5 and Severity: normal and unassigned?