Public bug reported:
Summary
After upgrading to Kubuntu 26.04 LTS, the final Plymouth frame freezes
at the end of boot and remains briefly visible both before SDDM appears
and again during the transition from SDDM to the KDE Plasma desktop
session.
This issue did not occur on Kubuntu 25.10 using the same hardware and
configuration.
System Information
OS: Kubuntu 26.04 LTS
Desktop Environment: KDE Plasma
Display Manager: SDDM
Session Type: Both Wayland and X11
Boot Splash: Plymouth
Description
At the end of boot, Plymouth appears to quit but its final frame remains
frozen on screen momentarily before SDDM starts.
After logging into SDDM, the same frozen Plymouth frame briefly
reappears during Plasma startup before the desktop loads.
The issue appears to be a leftover framebuffer image rather than
Plymouth actively restarting.
Steps to Reproduce
Boot the system normally.
Observe Plymouth during the end of boot.
Wait for the SDDM login screen.
Log into a Plasma session.
Observe the transition to the desktop.
Observed Behavior
Sequence observed:
Plymouth animation runs normally during boot.
The final Plymouth frame freezes briefly before SDDM appears.
SDDM login screen appears.
User logs in.
The frozen Plymouth frame briefly reappears for approximately 1–2 seconds.
Screen turns black briefly.
Plasma desktop loads normally.
Expected Behavior
Plymouth should fully disappear once boot is complete.
No frozen Plymouth image should remain visible before SDDM starts.
Transition from SDDM to Plasma should occur without residual Plymouth frames
appearing.
Additional Information
The issue started only after upgrading to Kubuntu 26.04.
Kubuntu 25.10 on the same machine did not exhibit this behavior.
KDE splash screen is disabled.
The issue occurs in both Wayland and X11 sessions.
Another user suggested the frozen image may be leftover framebuffer contents
after Plymouth exits rather than Plymouth restarting.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: kubuntu-desktop 1.496
ProcVersionSignature: Ubuntu 7.0.0-15.15-generic 7.0.0
Uname: Linux 7.0.0-15-generic x86_64
ApportVersion: 2.34.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Sat May 16 23:02:38 2026
InstallationDate: Installed on 2026-03-26 (51 days ago)
InstallationMedia: Kubuntu 25.10 "Questing Quokka" - Release amd64 (20251007)
SourcePackage: kubuntu-meta
UpgradeStatus: Upgraded to resolute on 2026-05-14 (2 days ago)
** Affects: kubuntu-meta (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute
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https://bugs.launchpad.net/bugs/2152814
Title:
Frozen Plymouth frame remains visible before SDDM and during Plasma
session startup on Kubuntu 26.04
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