Dear Maintainer,

   * What led up to the situation? three-monitors setup: laptop + 2 screens
connected to a USB-C (non-thunderbolt) dock
   * What exactly did you do (or not do) that was effective (or
     ineffective)? disconnect the dock
   * What was the outcome of this action? All displayed app crash.
   * What outcome did you expect instead? Windows should get respositioned on
the laptop screen.

Not sure at all, but itmaybe this bug is relevant "wayland: Check for nullptr
output in ColorManagementOutputV1" >
https://invent.kde.org/plasma/kwin/-/merge_requests/8029?file=f3e7c51f550d1f9eead066bfc3b1a6fabc24e938#diff-
content-f3e7c51f550d1f9eead066bfc3b1a6fabc24e938

It's kwin crashing, not just the apps displayed. I sent the debug info
generated via the crash handler reporting tool right now.

severity -1 important

Hi Claudio,
screens
respositioned on

Yes, the bug is known to us, but unfortunately it is not possible to
backport that patch to Plasma 6.3. At least I haven't found a way as
kwin fails to build with it.

I understand. Thanks anyway for your help and dedication!


Il giorno gio 2 ott 2025 alle ore 20:12 Patrick Franz <deltaone@debian.org>
ha scritto:

severity -1 important

Hi Claudio,
screens
respositioned on

Yes, the bug is known to us, but unfortunately it is not possible to
backport that patch to Plasma 6.3. At least I haven't found a way as
kwin fails to build with it.

I can confirm the bug for two Lenovo Thunderbolt docks, one tb3, one tb4.

Kindest regards,
	Dietz

I mean, it *can* be backported, I'm currently running this patch and it
seems to work fine.

I tested by plugging/unplugging a USB-C docking adapter a few times,
also powering off/on the monitor while attached, and everything worked.

However, I only encountered the bug once (after unplugging the same
USB-C adapter) and cannot reproduce it reliably, so my testing is
obviously limited.

Anyway, feel free to use this patch if you want :)

Hi all,

Am Sonntag, 19. Oktober 2025, 21:12:22 Mitteleuropäische Sommerzeit
schrieb debianuser@sfr.fr:
Unstable is in the process of getting updated to Plasma 6.5.0 which this
bug is fixed, so no point in backporting for that.

You can find the rebuilt packages here:
https://people.debian.org/~deltaone/kwin_docking_station/

You can find the packages in the respective subfolder. I'd be very
thankful if people could test it. If it works, I can backport officially
to trixie.

Hello Patrick,

I would have loved to report success, but sadly no: on a forky updated system,
an unplug of my USB-C dock (with two DisplayPort-attached screens) still
crashes kwin_wayland. I've tried straight post upgrade, and post-reboot too,
to no avail.

I also tried to upgrade to experimental's kwin/plasma/etc, but didn't manage
to get to a point where my sddm or desktop sessions were starting reliably.
(And I need to revise my downgrading fu, it took me way too long to get all
packages back to the forky/testing versions).

Thanks for your efforts, best,

OdyX

Thanks a lot Patrick, this patch seems to work on my home setup! I'll test
some more tomorrow on my office setup, which is the one that reliably used
to trigger the bug each and every time, and get back to y'all.

Il giorno mar 21 ott 2025 alle ore 19:02 Patrick Franz <deltaone@debian.org>
ha scritto:

Le mercredi, 22 octobre 2025, 10.19:34 h heure normale d’Europe centrale
Didier 'OdyX' Raboud a écrit :
wrote:

Now, with kwin-wayland 4:6.5.0-1 in testing, I don't have the crashes anymore.

Closing as fixed in that version.

Best,
OdyX

I'd like to add that the only thing crashing upon dock disconnection, after
installing your patches, is Firefox! It seems like a good improvement, I'd
still publish them!

Il giorno gio 30 ott 2025 alle ore 08:09 Debian Bug Tracking System <
owner@bugs.debian.org> ha scritto: