Public bug reported:
After upgrading from Ubuntu 24.04.5 LTS to 26.04.1 LTS on 28 October
2026, graphical login failed. Instead of my normal desktop, I
encountered an incomplete, default-like session environment.
**Investigation**
Affected file: `/usr/share/gdm/greeter/wayland-sessions/gnome-
greeter.desktop`
The official `gdm3` package still ships:
`Exec=gnome-session`
Changing it to:
`Exec=gnome-session --session=gnome-login`
restored normal graphical login.
I verified the original file directly in the downloaded Ubuntu DEB
package.
Installed versions:
- `gdm3`: 50.1-0ubuntu0.1
- `gnome-session-bin`: 50.1-0ubuntu0.1
- `gnome-session`: no version reported by `dpkg-query -W`
`dpkg -V gdm3` reports a checksum mismatch because of my manual
workaround, not because the original file was modified during the
upgrade.
`adsys` is not installed on this system.
**Expected:** GDM starts the greeter correctly and allows normal user
login.
**Actual:** Graphical login failed until the greeter session was
explicitly specified.
**Open question:** Why does the default `Exec=gnome-session` fail to
select the correct greeter session on this system?
**Hardware:** AMD Ryzen 5 2400G, integrated Radeon Vega graphics.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: gdm3 50.1-0ubuntu0.1 [modified:
usr/share/gdm/greeter/wayland-sessions/gnome-greeter.desktop]
ProcVersionSignature: Ubuntu 7.0.0-43.43-generic 7.0.14
Uname: Linux 7.0.0-43-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Nov 8 00:08:45 2026
InstallationDate: Installed on 2025-07-13 (482 days ago)
InstallationMedia: Ubuntu 22.04.4 LTS "Jammy Jellyfish" - Release amd64
(20240220)
ProcEnviron:
LANG=de_DE.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: gdm3
UpgradeStatus: Upgraded to resolute on 2026-10-27 (11 days ago)
** Affects: gdm3 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2173659
Title:
GDM greeter fails to start correct session after Ubuntu 26.04.1
upgrade; explicit gnome-login session fixes login
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