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Topic: [SOLVED] Qt incompatibility with 6.7.1 is stopping my KDE session from starting? (Read 923 times) previous topic - next topic
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[SOLVED] Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

When I try to start a KDE Plasma session from SDDM it times out on the spinning cog, and ~/.local/share/sddm/xorg-session.log contains, in part:

Code: [Select]
Initializing "/usr/lib/qt6/plugins/plasma/kcms/systemsettings/kcm_fonts.so"
org.kde.plasma.session: process job "kcminit_startup" finished with exit code 0
Cannot mix incompatible Qt library (6.7.1) with this library (6.7.2)
<end of file>

It's not clear to me what "this" is referring to but presumably systemsettings.

I've done an update but weirdly the problems didn't seem to start until sometime after updating. Suddenly alt tab stopped working and other basic KDE functionality, like the Meta button opening my launcher.

Does anyone know how to get more information and/or fix this?

pacman shows I have version 6.7.2-1 of qt6-base

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #1 –
Code: [Select]
pacman -Q|grep qt6-
Will show you most of the likely candidates for which qt package is still on 6.7.1.

Often just updating again will fix it once your mirror has caught up.

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #2 –
Quote from: gripped – on
Code: [Select]
pacman -Q|grep qt6-
Will show you most of the likely candidates for which qt package is still on 6.7.1.

Often just updating again will fix it once your mirror has caught up.

Interesting, none of my packages are actually still on 6.7.1. Would it be worth it to reinstall them?

Code: [Select]
$ pacman -Q|grep 6.7.2
libldap 2.6.7-2
qt6-5compat 6.7.2-1
qt6-base 6.7.2-1
qt6-declarative 6.7.2-1.1
qt6-imageformats 6.7.2-1
qt6-location 6.7.2-1
qt6-multimedia 6.7.2-1
qt6-multimedia-ffmpeg 6.7.2-1
qt6-networkauth 6.7.2-1
qt6-positioning 6.7.2-1
qt6-quick3d 6.7.2-1.1
qt6-quicktimeline 6.7.2-1
qt6-scxml 6.7.2-1
qt6-sensors 6.7.2-1
qt6-shadertools 6.7.2-1
qt6-speech 6.7.2-1
qt6-svg 6.7.2-1
qt6-tools 6.7.2-1
qt6-translations 6.7.2-1
qt6-virtualkeyboard 6.7.2-1
qt6-wayland 6.7.2-1
qt6-webchannel 6.7.2-1
qt6-webengine 6.7.2-1
qt6-websockets 6.7.2-1

Could there be some non-qt-branded KDE Plasma packages that depend on 6.7.1, but it wouldn't be obvious from their names?

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #3 –
I've just remembered there was a similar issue to this a while back and it turned out to be one of the theming engines / config programs.
I can't find the thread and can't remember the name though sorry.

At a wild guess do you have qt6ct installed? Or maybe kvantum ?
Make sure everything from the AUR (if any) is up to date.

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #4 –
You need a pacman hook for every qt6 program that was compiled from scratch and installed systemwide that will recompile them whenever there's qt6-base (and probably several others) update.

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #5 –
I don't think I compiled anything directly. I do have some packages installed with yay, so I did a yay -Syu (and had forgotten to do so in some time) but that didn't change the problem.

I tried with a new user account too:

Code: [Select]
QIODevice::readLine (QFile, "/home/test/.config/kdedefaults/package"): device not open
QPixmap: QGuiApplication must be created before calling defaultDepth().
QPixmap: QGuiApplication must be created before calling defaultDepth().
Initializing  "/usr/lib/qt6/plugins/plasma/kcms/systemsettings/kcm_mouse.so"
Initializing  "/usr/lib/qt6/plugins/plasma/kcms/systemsettings/kcm_style.so"
Initializing  "/usr/lib/qt6/plugins/plasma/kcms/systemsettings/kcm_fonts.so"
org.kde.plasma.session: process job  "kcminit_startup" finished with exit code  0
Cannot mix incompatible Qt library (6.7.1) with this library (6.7.2)

pkgfile reports that kcm_fonts.so (if that's the issue, in systemsettings) is provided by:
Code: [Select]
 
$ pkgfile /usr/lib/qt6/plugins/plasma/kcms/systemsettings/kcm_fonts.so
world/plasma-workspace
extra/plasma-workspace

I'm not sure which repo mine comes from, but it says the package maintainer is from artixlinux.org:
Code: [Select]
$ pacman -Qi plasma-workspace
Name            : plasma-workspace
Version         : 6.1.0-1
Description     : KDE Plasma Workspace
Architecture    : x86_64
URL             : https://kde.org/plasma-desktop/
Licenses        : LGPL-2.0-or-later
Groups          : plasma
Provides        : None
...
powerdevil-light  xdg-desktop-portal-kde
Optional For    : openbox
Conflicts With  : plasma-wayland-session
Replaces        : plasma-wayland-session
Installed Size  : 54.50 MiB
Packager        : nikolar <[email protected]>
Build Date      : Thu 20 Jun 2024 10:09:17 AM MDT
Install Date    : Mon 24 Jun 2024 09:33:05 PM MDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

And it seems up to date.

It's weird my KDE just self destructed. I'm not sure if that error message indicates the systemsettings plugin is really the issue or not

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #6 –
A guy on the KDE forums suggested this was caused by the package maintainer not updating KDE components properly, while updating QT prematurely. I have my doubts.
 

Re: A Qt incompatibility with 6.7.1 is stopping my KDE session from starting?

Reply #8 –
Quote from: nous – on
Quote from: user0938490 – on
A guy on the KDE forums suggested this was caused by the package maintainer not updating KDE components properly, while updating QT prematurely. I have my doubts.
Is qt6gtk2 installed? Does qt6gtk2-0.2-3.8 solve your issue?

Just this morning the packages "qt6gtk2" and "qt5-styleplugins" got an update from 0.2-3.7 to 0.2-3.8 and 5.0.0.20170311-42 to 5.0.0.20170311-43 (which I bet is no surprise to you, given the packager field for those packages  ;) ) and it works now! Thanks for the update!