Hi Merlin, I'm trying to fully understand your scenario/configuration.

In Nightly on Windows (20191020094538):

• I enabled Restore Previous Session + Warn you when quitting the browser on about:preferences#general

• I opened three tabs in a regular window

• I launched a private window and opened a couple of tabs

Test #1:

• I closed the regular window: there was no warning about closing tabs or quitting

• I closed the private window

• At the next startup, the regular window restored

Test #2:

• I used menu > Exit in the private window: there was no warning

• At the next startup, the regular window restored

Test #3:

• I used menu > Exit in the regular window: there was no warning

• At the next startup, the regular window restored

It's strange that I never get a warning, but it's comforting that the session is restored.

How is my test different from your scenario?

Hi and thanks for the fast response :)

Actually I Restore Previous Session enabled and I don't have "Warn you when quitting the browser" enabled but I have the option "Warn you if multiple tabs are about to be closed" enabled, which I can only find when closing multiple tabs at once.

Regarding the testcases:

Test #1: - Works as you describe for me so long as I close the private window (session gets restored), but if I do not close the private Tabs and reopen a regular window, the tabs are not restored.

Test #2 and #3: - Work as you described (in both cases both windows close without a warning and the regular window gets restored afterwards)

My Firefox is a 71.0b2 (64-Bit) Developer Edition

You need to exit/quit Firefox with the non private window still open. If you first close this non private window, but still have a PB mode window open and close this as the last window then Firefox won't restore this non private window. In such a case you can still check "History -> Recently Closed Tabs/Windows" after the restart.

Merlin said

Test #1:
- Works as you describe for me so long as I close the private window (session gets restored), but if I do not close the private Tabs and reopen a regular window, the tabs are not restored.

How are you reopening the regular window without closing the private window? For example:

• "3-bar" menu button > Library > History > Recently Closed Windows
• Library toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows
• Ctrl+Shift+n

Do you get:

• Menu is grayed out
• Closed window is not listed on the menu
• Closed window is listed and can be restored, but some tabs are missing
• Closed window is listed and can be restored with all tabs, but some tabs are unloaded (only load when you activate the tab)

Thanks for your answers :)

@cor-el said

You need to exit/quit Firefox with the non private window still open. If you first close this non private window, but still have a PB mode window open and cklose this as the last window then Firefox won't restore this non private window.

Interestingly, if I close the (remaining) private window after I closed the regular window, it automatically restores my session when reopening a regular window (even though it warned me before). This is not the case if I reopen the regular window (via the taskbar) without closing the private window beforehand.

cor-el said

In such a case you can still check "History -> Recently Closed Tabs/Windows" after the restart.

That's usually true, but in rare cases I've lost my session (it didn't show up in the history menu, especially when some downtime is between the closing and the re-opening). But never the less thanks for this advice, it already helped me :)

@jscher2000 My window reopening method is via the taskbar (just opening a new window). Reopening the regular window via the 4 ways you described works without problems (as long as the window is in the list), but opening a new window doesn't pick up the recently closed window as it would if the private window were not present.

I remember losing the window history after some downtime (e.g., after system shutdown) though, which happened to me a couple of times in the past but wasn't able to replicate this behavior (maybe an old problem that was fixed...)

Merlin said

@jscher2000 My window reopening method is via the taskbar (just opening a new window). Reopening the regular window via the 4 ways you described works without problems (as long as the window is in the list), but opening a new window doesn't pick up the recently closed window as it would if the private window were not present.

Hmm, it sounds as though Firefox is still running (at least one window open). So launching a new window through the Taskbar Jump List simply adds a window to the same session rather than starting a new session. I don't think there's any trick to make Firefox re-run a session restore without starting a new session, which would mean closing/losing your private window. So I think you'll have to use the Recently Closed Windows list or Ctrl+Shift+n, or find an add-on to do it, if one exists for that.

jscher2000 said

Merlin said

@jscher2000 My window reopening method is via the taskbar (just opening a new window). Reopening the regular window via the 4 ways you described works without problems (as long as the window is in the list), but opening a new window doesn't pick up the recently closed window as it would if the private window were not present.

Hmm, it sounds as though Firefox is still running (at least one window open). So launching a new window through the Taskbar Jump List simply adds a window to the same session rather than starting a new session. I don't think there's any trick to make Firefox re-run a session restore without starting a new session, which would mean closing/losing your private window. So I think you'll have to use the Recently Closed Windows list or Ctrl+Shift+n, or find an add-on to do it, if one exists for that.

I guess that private window and not private window must have own isolated session. And then was not any problem

Hi Destructor, the tabs in private windows are not saved in the session history file on disk and cannot be restored once the private window is closed. That is the same regardless of the order different windows are closed.