Public bug reported:
# Bug report draft — display flicker on Skylake after Ubuntu 26.04
upgrade
## Suggested target package
`gnome-shell` (primary symptom is in mutter/gnome-shell GBM buffer handling on
Wayland).
Affects-also candidates: `mutter`, `mesa`, `linux` (Skylake i915).
## Suggested title
gnome-shell Wayland: repeated `gbm_surface_lock_front_buffer failed` / EGL
error 3003 on Skylake (HD 530) after upgrade to Ubuntu 26.04, causing display
flicker on multi-monitor setup
## Body
### Summary
After upgrading from Ubuntu 25.10 to Ubuntu 26.04 LTS (resolute), display
flicker
appeared on a Skylake-based desktop driving three external displays via a dock.
Two distinct flicker sources have been observed across the upgrade. The
original,
pre-upgrade kernel-side errors on i915 (atomic update failures on the display
pipes) can be silenced by disabling i915 power-save features at boot. However,
after the 26.04 upgrade a new, userspace-side symptom appeared and recurs:
gnome-shell on Wayland repeatedly fails to lock the front buffer on the i915
DRM device, which correlates in time with the visible flicker.
### Steps to reproduce
1. Boot Ubuntu 26.04 with kernel 7.0.0-15-generic on Skylake (Gen9, HD Graphics
530).
2. Log in to the default GNOME Shell 50 Wayland session.
3. Use a multi-monitor (3-external-display) setup driven by the iGPU through a
dock
(in this case: DisplayPort + DisplayPort + HDMI; mixed refresh / resolution
per display).
4. Use the desktop normally for some minutes.
### Expected
No flicker. Stable scanout on all three displays.
### Actual
- Visible flicker on the external displays during normal desktop use.
- `journalctl --user` shows repeated bursts of, from `gnome-shell`:
Failed to query buffer age, got error 3003
Failed to lock front buffer on /dev/dri/card1:
gbm_surface_lock_front_buffer failed
(EGL error 3003 == EGL_BAD_SURFACE.)
- The bursts correlate in time with the visible flicker.
- Kernel/i915 log is clean during these events on the upgraded system
(no `Atomic update failure on pipe …`, no FIFO underruns, no GPU hangs),
i.e. the new failure is on the userspace/compositor side, not in the i915
atomic path.
### Pre-upgrade vs post-upgrade behaviour
- Pre-upgrade (Ubuntu 25.10, kernel 6.17.0-29-generic), the flicker symptom was
kernel-side: `i915 *ERROR* Atomic update failure on pipe C` (and pipes A/B
on later occurrences). Disabling i915 power-save features
(`i915.enable_psr=0 i915.enable_fbc=0 i915.enable_dc=0
i915.enable_dpcd_backlight=0`
on the kernel command line) silenced the kernel errors and visibly reduced
flicker.
- Post-upgrade (Ubuntu 26.04, kernel 7.0.0-15-generic), the same boot parameters
are active and the kernel-side errors are indeed absent, but the new userspace
GBM lock failure described above appears and the flicker has returned with
a different signature.
### Active kernel command line
BOOT_IMAGE=/vmlinuz-7.0.0-15-generic root=/dev/mapper/… ro quiet splash \
i915.enable_psr=0 i915.enable_fbc=0 i915.enable_dc=0
i915.enable_dpcd_backlight=0 \
crashkernel=…
### Environment
- Distribution: Ubuntu 26.04 LTS (resolute)
- Kernel: 7.0.0-15-generic (#15-Ubuntu SMP PREEMPT_DYNAMIC, built 2026-04-22)
- Session type: Wayland
- Compositor / shell: gnome-shell 50.1-0ubuntu1
- Mesa: 26.0.3-1ubuntu1
- libdrm2: 2.4.131-1
- CPU: Intel Core i5-6500T (Skylake)
- GPU: Intel Corporation Skylake-S GT2 [HD Graphics 530] [8086:1912] rev 06
- Internal eDP: disabled by kernel at boot
i915 0000:00:02.0: [drm] [ENCODER:109:DDI A/PHY A] failed to retrieve link
info, disabling eDP
- Displays (all external via dock):
- DP-1 1920x1080 @ 60 Hz (primary)
- DP-3 1440x900 @ 60 Hz
- HDMI-2 1680x1050 @ 60 Hz
- DRM device numbering on this kernel:
- card0 = `simpledrm` (early framebuffer)
- card1 = `i915` (the device gnome-shell operates on, per the error message)
### Relevant log excerpt (userspace, repeating bursts)
gnome-shell[…]: Failed to query buffer age, got error 3003
gnome-shell[…]: Failed to lock front buffer on /dev/dri/card1:
gbm_surface_lock_front_buffer failed
gnome-shell[…]: Failed to query buffer age, got error 3003
gnome-shell[…]: Failed to lock front buffer on /dev/dri/card1:
gbm_surface_lock_front_buffer failed
…
### Relevant kernel log excerpt at i915 init (this boot)
i915 0000:00:02.0: [drm] Found skylake (device ID 1912) integrated display
version 9.00 stepping G0
i915 0000:00:02.0: [drm] Finished loading DMC firmware
i915/skl_dmc_ver1_27.bin (v1.27)
i915 0000:00:02.0: [drm] [ENCODER:109:DDI A/PHY A] failed to retrieve link
info, disabling eDP
i915 0000:00:02.0: [drm] Registered 3 planes with drm panic
[drm] Initialized i915 1.6.0 for 0000:00:02.0 on minor 1
No `Atomic update failure`, no `FIFO underrun`, no GPU/GuC reset messages in the
kernel log during the flicker on this kernel/distro combination.
### What has NOT yet been tried (planned bisection)
- Booting the still-installed previous kernel 6.17.0-29-generic on the same
Ubuntu 26.04 userspace, to isolate whether the regression is in kernel 7.0
i915 (Skylake/Gen9) or in the 26.04 userspace stack.
- Logging in via an "Ubuntu on Xorg" GDM session instead of Wayland, to isolate
whether the regression is in mutter/Wayland buffer handling.
- Disabling additional new i915 power-save flags introduced in 7.0
(`enable_dmc_wl`, `enable_psr2_sel_fetch`, `enable_panel_replay`).
- `i915.disable_power_well=1` as a last-resort kernel mitigation.
(Happy to run these and attach results if helpful.)
### Impact
Multi-monitor desktop usage on a previously-stable Skylake machine is again
affected by visible flicker after the 26.04 upgrade. Existing community
mitigations for the old kernel-side symptom no longer address the new
userspace-side symptom.
### Notes for triage
- The visible regression is correlated specifically with the upgrade window
(distro upgrade performed 2026-05-18; new symptom observed on 26.04 only).
- Hardware did not change across the regression.
- This may be relevant to other Gen9 (Skylake/Kaby Lake) users on multi-display
iGPU-only setups upgrading to 26.04.
** Affects: gnome-shell (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2154295
Title:
Occasional Flickering happened AFTER upgrade to Ubuntu 26.04
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