[SOLVED] Problem with 2 monitors - solution inside

[Solo0815]

I upgraded Kubuntu 24.04 to 24.10 beta. Now I can't get dual monitors to work. If I plugin a second Monitor or start with 2 monitors plugged in, I get a black screen with only the mouse cursor showing up. No rightclick-menu or other menu is working. The bar on the bottom is also gone.

Edit: solution is in the 2nd post.

With only one monitor plugged in, I have the normal desktop. If I plug in the second monitor, I get a reproducable black screen as described above.
It happens with X11 and wayland.
1st monitor: HP w2208h (1680x1050)
2nd monitor: Iiyama 2730h (1920x1080) This one is not working and plugged out to get a desktop while testing

Here is the dmesg-output:
https://pastebin.com/QHjczgVi

I see some error regarding apparmor (DENIED) and plasmashell after plugging in the second monitor.

[ 6393.475040] audit: type=1400 audit(1727796656.562:41439): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14557 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6393.485991] audit: type=1400 audit(1727796656.573:41440): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14558 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6393.495670] traps: plasmashell[2525] trap int3 ip:780d4cf7cb41 sp:7ffc1c391500 error:0 in libQt6WebEngineCore.so.6.6.2[3b7cb41,780d49f51000+8cd1000]
[ 6404.026157] ibus-ui-gtk3[2965]: segfault at 0 ip [URL="tel:0000000000000000"]0000000000000000[/URL] sp 00007ffc50f19468 error 14 likely on CPU 2 (core 2, socket 0)
[ 6404.026167] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 6404.050535] fbcon: Taking over console
[ 6404.224780] Console: switching to colour frame buffer device 210x65
[ 6406.713515] audit: type=1400 audit(1727796669.801:41441): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14822 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6406.717757] audit: type=1400 audit(1727796669.805:41442): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14823 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6406.721376] traps: plasmashell[14763] trap int3 ip:76eb74f7cb41 sp:7ffeb9ca5370 error:0 in libQt6WebEngineCore.so.6.6.2[3b7cb41,76eb71f51000+8cd1000]
[ 6408.674411] audit: type=1400 audit(1727796671.762:41443): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14892 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6408.678980] audit: type=1400 audit(1727796671.766:41444): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14893 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6408.682935] traps: plasmashell[14834] trap int3 ip:747358f7cb41 sp:7ffe7e8b8210 error:0 in libQt6WebEngineCore.so.6.6.2[3b7cb41,747355f51000+8cd1000]
[ 6410.411720] audit: type=1400 audit(1727796673.499:41445): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14961 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6410.415979] audit: type=1400 audit(1727796673.503:41446): apparmor="DENIED" operation="exec" class="file" info="no new privs" error=-1 profile="plasmashell" name="/usr/lib/qt6/libexec/QtWebEngineProcess" pid=14962 comm="plasmashell" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="unconfined"
[ 6410.419445] traps: plasmashell[14903] trap int3 ip:7fd7d8f7cb41 sp:7fff50c60ec0 error:0 in libQt6WebEngineCore.so.6.6.2[3b7cb41,7fd7d5f51000+8cd1000]

Edit:
heres the gdb output:

[New LWP 2541]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007bd7ab3256a0 in __GI_ppoll (fds=0x5bc37a5b7570, nfds=10, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:42

warning: 42 ../sysdeps/unix/sysv/linux/ppoll.c: Datei oder Verzeichnis nicht gefunden
(gdb)
(gdb) continue
Continuing.
(gdb) [New Thread 0x7bd6fcc006c0 (LWP 5728)]
[Detaching after fork from child process 5729]
[Detaching after fork from child process 5730]
[Detaching after fork from child process 5731]

Thread 1 "plasmashell" received signal SIGTRAP, Trace/breakpoint trap.
0x00007bd614f7cb41 in ?? () from /lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6

Can anyone help?
Here is the bug-report in launchpad. Noone responded yet unfortunately. How can I use my second monitor again?
https://bugs.launchpad.net/ubuntu/+s...e/+bug/2083596
If you need additional info or want me to test something, pls let me know.

I posted this question/bug already in the "help the new guy"-forum here. At this time, there was no 24.10-section.Sorry for crossposting.

Thx in advance

[Solo0815]

I solved the issue by renaming plasmashellrc and plasma-org.kde.plasma.desktop-appletsrc
Now all my 2 monitors are working again.

If you want to have a look at the 2 files, I attached them to the launchpad-bug-report. See link above