That's a known issue, see https://forum.snapcraft.io/t/cannot-open- display-after-session-type-changed-wayland-x11/23838. The problem appears to be partly in gnome-session (https://gitlab.gnome.org/GNOME/gnome-session/-/issues/75), partly in the snapcraft desktop extensions that assume a wayland session if there's a lingering wayland socket (https://github.com/snapcore/snapcraft/blob/main/extensions/desktop/common/desktop- exports#L240).
It is not specific to the firefox snap, and it can be worked around by running the apps with DISABLE_WAYLAND=1. ** Bug watch added: gitlab.gnome.org/GNOME/gnome-session/-/issues #75 https://gitlab.gnome.org/GNOME/gnome-session/-/issues/75 ** Package changed: firefox (Ubuntu) => gnome-session (Ubuntu) ** Also affects: gnome-session via https://gitlab.gnome.org/GNOME/gnome-session/-/issues/75 Importance: Unknown Status: Unknown ** Also affects: snapcraft Importance: Undecided Status: New ** Summary changed: - Firefox 98.0.1-2 snap doesn't start at all in Xorg sessions if a Wayland session has been used + Desktop snaps don't start at all in Xorg sessions if a Wayland session has been used -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/1965113 Title: Desktop snaps don't start at all in Xorg sessions if a Wayland session has been used Status in gnome-session: Unknown Status in Snapcraft: New Status in gnome-session package in Ubuntu: New Bug description: Firefox 98.0.1-2 snap doesn't start at all in Xorg sessions. $ /snap/bin/firefox Error: cannot open display: :0 $ echo $DISPLAY :0 And other X11 apps still work just fine. To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-session/+bug/1965113/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp