Bug#1052374: gdm3: Shows only an error screen when gnome.session is missing

[Alper Nebi Yasak]

Package: gdm3
Version: 45~beta-1
Severity: serious
Justification: missing dependency to function properly
Control: -1 notfound 44.1-2

Dear Maintainer,

I've been using gdm3 without GNOME, and after recently upgrading gdm3 to
45~beta-1 I started getting the gray "Oh no!" error message instead of
the login screen.

Tried a few things and found installing the gnome-session package fixes
it. Copying /usr/share/gnome-session/sessions/gnome-login.session to
.../gnome.session also fixes it.

Looks like #850291, but that is archived and I don't know the Control
invocations I need to continue on top of that. Setting severity same as
that, though.

Thanks for all the work on GNOME. My system is a bit of a mess, so don't
hesitate to ask specifics if you can't reproduce the error.

-- System Information:
Debian Release: trixie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: arm64, armhf, armel, i386

Kernel: Linux 6.5.0-1-amd64 (SMP w/24 CPU threads; PREEMPT)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),
LANGUAGE=en_GB:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gdm3 depends on:
ii  accountsservice                       23.13.9-4
ii  adduser                               3.137
ii  dbus [default-dbus-system-bus]        1.14.10-1
ii  dbus-bin                              1.14.10-1
ii  dbus-daemon                           1.14.10-1
ii  dconf-cli                             0.40.0-4
ii  dconf-gsettings-backend               0.40.0-4
ii  debconf [debconf-2.0]                 1.5.82
ii  gir1.2-gdm-1.0                        45~beta-1
ii  gnome-session [x-session-manager]     45.0-1
ii  gnome-session-bin                     45.0-1
ii  gnome-session-common                  45.0-1
ii  gnome-settings-daemon                 45.0-1
ii  gnome-shell                           44.5-1
ii  gnome-terminal [x-terminal-emulator]  3.50.0-1
ii  gsettings-desktop-schemas             45.0-1
ii  kwin-x11 [x-window-manager]           4:5.27.8-1
ii  libaccountsservice0                   23.13.9-4
ii  libaudit1                             1:3.1.1-1
ii  libc6                                 2.37-10
ii  libcanberra-gtk3-0                    0.30-10
ii  libcanberra0                          0.30-10
ii  libgdk-pixbuf-2.0-0                   2.42.10+dfsg-1+b1
ii  libgdm1                               45~beta-1
ii  libglib2.0-0                          2.78.0-2
ii  libglib2.0-bin                        2.78.0-2
ii  libgtk-3-0                            3.24.38-5
ii  libgudev-1.0-0                        238-2
ii  libkeyutils1                          1.6.3-2
ii  libpam-modules                        1.5.2-7
ii  libpam-runtime                        1.5.2-7
ii  libpam-systemd [logind]               254.3-1
ii  libpam0g                              1.5.2-7
ii  librsvg2-common                       2.54.7+dfsg-2
ii  libselinux1                           3.5-1
ii  libsystemd0                           254.3-1
ii  libx11-6                              2:1.8.6-1
ii  libxau6                               1:1.0.9-1
ii  libxcb1                               1.15-1
ii  libxdmcp6                             1:1.1.2-3
ii  lxterminal [x-terminal-emulator]      0.4.0-2
ii  metacity [x-window-manager]           1:3.49.1-1
ii  polkitd                               123-1
ii  procps                                2:4.0.3-1
ii  qterminal [x-terminal-emulator]       1.3.0-1
ii  rxvt-unicode [x-terminal-emulator]    9.31-1
ii  systemd-sysv                          254.3-1
ii  ucf                                   3.0043+nmu1
ii  x11-common                            1:7.7+23
ii  x11-xserver-utils                     7.7+9+b1
ii  xfce4-session [x-session-manager]     4.18.3-1
ii  xfce4-terminal [x-terminal-emulator]  1.1.0-1
ii  xfwm4 [x-window-manager]              4.18.0-1
ii  xterm [x-terminal-emulator]           384-1

Versions of packages gdm3 recommends:
ii  at-spi2-core                       2.50.0-1
ii  desktop-base                       12.0.6+nmu1
ii  gnome-session [x-session-manager]  45.0-1
ii  x11-xkb-utils                      7.7+7
ii  xfce4-session [x-session-manager]  4.18.3-1
ii  xserver-xephyr                     2:21.1.8-1
ii  xserver-xorg                       1:7.7+23
ii  zenity                             3.44.2-1

Versions of packages gdm3 suggests:
pn  libpam-fprintd        <none>
ii  libpam-gnome-keyring  42.1-1+b2
pn  libpam-pkcs11         <none>
pn  libpam-sss            <none>
ii  orca                  45.0-1

-- debconf information:
* shared/default-x-display-manager: gdm3
  gdm3/daemon_name: /usr/sbin/gdm3