Firefox ESR gives me "Already Running" error when opening new window


I seem to have a similar problem as mentioned in this post. Sadly there is no solution given.

I use Ubuntu 22.04 LTS Mate and changed from the default firefox snap to the esr/stable channel. The Ubuntu installation is “fresh” (no upgrade from previous), but has a few other things installed.

With firefox esr I get the following error whenever I try to open a new window via the firefox icon or command line and a firefox window is already open:

Firefox is already running, but is not responding. To use Firefox, you must first close the existing Firefox process, restart your device, or use a different profile.

The open window reacts normally, no problems there. I can drag a tab out to create a new window just fine. This happens on different user-accounts (probably all).

With the default version (latest/stable) a second window would open (like expected) - so it may have to to with differences in the esr version.

Is there anything I need to change in order to fix the problem? I would prefer to continue to use the ESR version as I configure ff via the policies file for multiple users, including options that are only available on ESR.

Additional info:
Session-Type: X11
firefox-snap-version: 115.2.1esr-1 (3130)
Output of env | egrep -i "session|moz":

SESSION_MANAGER=local/:@/tmp/.ICE-unix/2374,unix/:/tmp/.ICE-unix/2374 XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0

Whenever I start firefox esr via commandline I get this info - then firefox starts normally (first window) or gives the mentioned error:

Gtk-Message: 13:24:06.805: Failed to load module “appmenu-gtk-module”
Gtk-Message: 13:24:06.805: Not loading module “atk-bridge”: The functionality is provided by GTK natively. Please try to not load it.

I have not tested if I get the same info on the regular firefox version.


small update: I get the same error message (failed to load appmenu-gtk-module …) also with regular firefox - so this is probably not the problem or at least not the main cause.

I also tried to install firefox esr (firefox-115.2.1esr) via download from mozilla (unpacked to /opt) - no problem with opening a second window with that version.

So it seems like the error with not being able to open a second window is a snap problem.

For now, I’ll probably go with the non-ESR Firefox snap, since that’s less hassle for me than manually installing (and updating) firefox.

If anyone has any ideas on how to fix the esr snap issue on my end, I’d still love to hear them.

bump - from very short testing the same issue is still present with the 115.8.0esr-1 snap version (esr/stable).