I use several spaces on my iMac. When i start an application it always open in the current space, except Firefox who will start in the last space it used. This is really annoying because I have to switch to the space Firefox decided to start in which almost never is the space i have selected.

Is this a bug in Firefox, or is it a setting I have that causes this behavior?

  1. Settings in the Dock is not what cause this behavior:

    Settings in the Dock

  2. I tried to use the Dock setting "This Desktop" and the only difference is that when it is enabled, the selected Desktop/Space is switched into view. When I disable "This Desktop", Firefox still launches in the last used Desktop/Space, but the Desktop/Space is not switched into view.

  3. I reinstalled Firefox (dragged the app to trash, downloaded from Mozilla and installed) to no avail. I noticed that all settings and history was retained, so perhaps the problem is hidden in the stored data or settings that was not wiped. Will try to wipe all user data.

2 Answers 2


There is no preference setting for 'last Space used'.

There is 'All Desktops' [which makes the app follow you to all Spaces], This Desktop', [which is what I presume you have set] & 'None' [which has no affinity at all & should always start on the current Space].
These do not apply to fullscreen Spaces, only 'regular' Spaces.

You can access the setting by right clicking the app icon in the Dock, then Options…

enter image description here
If you are not on 'this desktop' when you access the option, it will show an additional item, showing the Space number.

enter image description here

Apple has always used the terms Desktop and Space interchangeably.

  • Thanks for you answer. Settings in the dock is default, so it is something else that cause this behavior. I updated my question to reflect this,
    – Mike
    Commented Jan 16, 2023 at 18:53
  • I made a correction to my bracketed definitions, which were in error - but that doesn't affect your new information. Are you certain this is from 'quit' i.e. the app is not running before you do this, as opposed to 'running but no windows open'. In effect, does the app have a dot below its icon in the Dock before you do this or not?
    – Tetsujin
    Commented Jan 16, 2023 at 18:59
  • Yes, the application is properly terminated: $ ps -A | grep -i fire" returns null.
    – Mike
    Commented Jan 16, 2023 at 19:03
  • I have no clue what that means. I'm a user not a coder. ;) Dot or no dot is sufficient information, really.
    – Tetsujin
    Commented Jan 16, 2023 at 19:04
  • Sorry :) The correct answer is NO DOT.
    – Mike
    Commented Jan 16, 2023 at 19:07

I figured out what caused this problem. In Settings, tab "General", there is an option "Open previous Windows and tabs" that is causing the issue for me. If I uncheck this option, Firefox launch in the current Desktop/Space. If it is checked, it launches in whatever Desktop/Space that was last used and if "Assign To | This Desktop" in the Dock is not selected, the Desktop/Space that Firefox reside in will not be switched to, thus Firefox launch silently out of the users view.

This must be a bug. Filed: https://bugzilla.mozilla.org/show_bug.cgi?id=1810591

enter image description here

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