Public bug reported:
I have a laptop (1920x1200) and an external monitor connected via HDMI
(3840x2160) and I had locked my computer and turned off my external
monitor. Note that I have previously configured Ubuntu to never send
"power save" signal to external monitor as Gnome interpreted this as if
I had physically removed the external display (this is a known problem
as I understand it -- this bug report is *not* about that issue (but it
might be related in some way)).
Note that I have Fractional Scaling enabled and laptop display is set to
100% scaling and external 4K monitor is set to 150% scaling.
Initial state is thus laptop running Ubuntu that is attached to an
external 4K monitor. After screen was locked (via Windows-l key
combination) external monitor was turned off (via physical button on
monitor). Laptop screen shows login dialog with correct resolution.
To trigger the bug I turn on the external 4K monitor (via physical
button). This results in external monitor going on but showing a black
picture. The laptop monitor (with login dialog) is scaled as if it
showed a 4K image on the 1920x1200 screen (you almost need magnifying
glasses to be able to see what you are doing on that screen). After
entering my password the laptop screen is unlocked (but still showing
the scaled resolution) and external monitor still shows a black picture.
Entering Ubuntu Settings App, selecting Displays and clicking on my
external monitor revealed that it had been disabled! Enabling external
monitor reset the resolutions of the monitors to what I expected (and
open applications are placed on the correct monitor).
Expected behavior is Ubuntu/Gnome *not* disabling the external display
when its power is turned off (via physical button on monitor) as it is
still electrically connected via HDMI-cable and monitors power cord is
still connected to the wall socket.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: xorg 1:7.7+23ubuntu3
ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-35-generic x86_64
.proc.driver.nvidia.capabilities.fabric-imex-mgmt:
DeviceFileMinor: 4323
DeviceFileMode: 256
DeviceFileModify: 1
.proc.driver.nvidia.capabilities.gpu0: Error: path was not a regular file.
.proc.driver.nvidia.capabilities.mig: Error: path was not a regular file.
.proc.driver.nvidia.gpus.0000.02.00.0: Error: path was not a regular file.
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
NVRM version: NVIDIA UNIX Open Kernel Module for x86_64 580.159.03 Release
Build (dvs-builder@U22-I3-AM27-29-6) Fri Apr 24 06:03:03 UTC 2026
GCC version: gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04.1)
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: pass
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Wed Jun 10 14:14:42 2026
DistUpgraded: Fresh install
DistroCodename: noble
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
Intel Corporation Arrow Lake-U [Intel Graphics] [8086:7d67] (rev 06) (prog-if
00 [VGA controller])
Subsystem: Dell Device [1028:0d12]
NVIDIA Corporation Device [10de:2c39] (rev a1) (prog-if 00 [VGA controller])
Subsystem: Dell Device [1028:0d12]
InstallationDate: Installed on 2026-05-02 (39 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: Dell Inc. Dell Pro Max 16 Plus MB16250
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-35-generic
root=UUID=8b298203-7cbd-41d8-a9f0-ebda6018a14b ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/19/2025
dmi.bios.release: 2.2
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 2.2.2
dmi.board.name: 0K8XPY
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.3
dmi.modalias:
dmi:bvnDellInc.:bvr2.2.2:bd11/19/2025:br2.2:efr1.3:svnDellInc.:pnDellProMax16PlusMB16250:pvr:rvnDellInc.:rn0K8XPY:rvrA01:cvnDellInc.:ct10:cvr:sku0D12:
dmi.product.family: Dell Pro Max Laptops
dmi.product.name: Dell Pro Max 16 Plus MB16250
dmi.product.sku: 0D12
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.125-1ubuntu0.1~24.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 25.2.8-0ubuntu0.24.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:21.1.12-1ubuntu1.5
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:22.0.0-1build1
version.xserver-xorg-video-intel: xserver-xorg-video-intel
2:2.99.917+git20210115-1build1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau
1:1.0.17-2ubuntu0.1
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble resolution ubuntu
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https://bugs.launchpad.net/bugs/2156353
Title:
Wrong resolution on primary (laptop) screen after turning on external
4K monitor
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