Public bug reported:
Ubuntu 24.04 Dell Vostro, hybrid Intel UHD 630 + NVIDIA GTX 1650 Mobile,
nvidia-driver-580-open 580.159.03, prime profile was on-demand.
2026-07-18 unattended-upgrade installed linux-image-7.0.0-28-generic and
linux-modules-nvidia-580-open-7.0.0-28-generic. First reboot after that
(2026-07-23) caused GDM login loop: password OK, then
"GdmDisplay: Session never registered, failing" with X11 RANDR BadValue
on NVIDIA (mode "NULL"); eDP is on i915.
Reproduced on both 7.0.0-28 and 6.17.0-40. Workaround: prime-select intel
(blacklist NVIDIA for display). Not caused by user autostart.
Hardware / software:
- Machine: jonathan-vostro (Dell Vostro laptop)
- OS: Ubuntu 24.04 LTS (Noble)
- GPUs: Intel CoffeeLake-H UHD Graphics 630 (boot VGA / internal panel)
NVIDIA GeForce GTX 1650 Mobile / Max-Q (TU117M)
- Driver package: nvidia-driver-580-open 580.159.03-0ubuntu0.24.04.1
- Display manager: gdm3
- Symptom: login screen loop (flash → back to GDM)
Trigger:
- Automatic update via /usr/bin/unattended-upgrade on 2026-07-18 ~06:04
- Packages: linux-image-7.0.0-28-generic,
linux-modules-nvidia-580-open-7.0.0-28-generic
- Last successful long GUI session started 2026-07-15 on kernel 6.17.0-40
- First reboot onto the new stack: 2026-07-23 → login loop
Technical failure:
- PAM auth succeeds (password correct)
- User X11 session fails within ~3 seconds
- journalctl: Gdm: GdmDisplay: Session never registered, failing
- X/NVIDIA: RANDR BadValue (RRSetProviderOutputSource); NVIDIA MetaMode "NULL"
- Internal display connected on Intel i915 (card1-eDP-1), not NVIDIA
Workaround applied:
sudo prime-select intel
(NVIDIA modules blacklisted; desktop runs on Intel / Mesa)
Verification commands after workaround:
prime-select query → intel
lsmod | grep '^nvidia' → empty
glxinfo -B | grep renderer → Mesa Intel UHD Graphics 630
nvidia-smi → cannot communicate with driver
Ruled out:
- Wrong password
- Disk full / home permissions
** Affects: ubuntu-release-upgrader (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2161673
Title:
Login screen loop after automatic updates
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