You need appropriate permission for its access:
# ls -ld /var/log/YaST2 /var/log/YaST2/y2log
drwx------ 10 root root 4096 Jun 26 13:54 /var/log/YaST2
-rw-r--r-- 1 root root 9942409 Jul 11 21:03 /var/log/YaST2/y2log
#
i did the search with root (sudo) account and i found nothing !
Are you missing any of the following packages that I have installed here?
# grep cpe /etc/os-release
CPE_NAME="cpe:/o:opensuse:tumbleweed:20230714"
# zypsei --no-refresh se -s -i yast ruby | grep -Ev 'debug|devel|srcp|openSUSE-20' | grep -E 'x86|noarch'| sort
i | libruby3_2-3_2 | package | 3.2.2-1.2 | x86_64 | OSS
i | libstorage-ng-ruby | package | 4.5.123-1.1 | x86_64 | OSS
i | ruby | package | 3.2-1.2 | x86_64 | OSS
i | ruby-common | package | 3.2.1-1.1 | noarch | OSS
i | ruby-solv | package | 0.7.24-1.3 | x86_64 | OSS
i | ruby3.2 | package | 3.2.2-1.2 | x86_64 | OSS
i | ruby3.2-rubygem-abstract_method | package | 1.2.1-2.31 | x86_64 | OSS
i | ruby3.2-rubygem-cfa | package | 1.0.2-1.18 | x86_64 | OSS
i | ruby3.2-rubygem-cfa_grub2 | package | 2.0.0-1.18 | x86_64 | OSS
i | ruby3.2-rubygem-cheetah | package | 1.0.0-1.10 | x86_64 | OSS
i | ruby3.2-rubygem-fast_gettext | package | 2.2.0-1.8 | x86_64 | OSS
i | ruby3.2-rubygem-gem2rpm | package | 0.10.1-21.1 | x86_64 | OSS
i | ruby3.2-rubygem-nokogiri | package | 1.13.9-1.6 | x86_64 | OSS
i | ruby3.2-rubygem-ruby-augeas | package | 0.5.0-3.33 | x86_64 | OSS
i | ruby3.2-rubygem-ruby-dbus | package | 0.23.0.beta2-1.1 | x86_64 | OSS
i | ruby3.2-rubygem-simpleidn | package | 0.2.1-1.13 | x86_64 | OSS
i | ruby3.2-rubygem-unf | package | 0.1.4-1.30 | x86_64 | OSS
i | ruby3.2-rubygem-unf_ext | package | 0.0.8.2-1.6 | x86_64 | OSS
i | yast2 | package | 4.6.2-1.1 | x86_64 | OSS
i | yast2-control-center | package | 4.6.1-1.1 | x86_64 | OSS
i | yast2-core | package | 4.6.0-1.3 | x86_64 | OSS
i | yast2-country-data | package | 4.6.2-1.1 | x86_64 | OSS
i | yast2-hardware-detection | package | 4.6.0-1.4 | x86_64 | OSS
i | yast2-logs | package | 4.6.2-1.1 | x86_64 | OSS
i | yast2-packager | package | 4.6.1-1.1 | x86_64 | OSS
i | yast2-perl-bindings | package | 4.6.0-1.3 | x86_64 | OSS
i | yast2-pkg-bindings | package | 4.6.2-1.2 | x86_64 | OSS
i | yast2-ruby-bindings | package | 4.6.2-1.2 | x86_64 | OSS
i | yast2-storage-ng | package | 4.6.12-1.1 | x86_64 | OSS
i | yast2-theme | package | 4.6.0-1.2 | noarch | OSS
i | yast2-transfer | package | 4.6.0-1.3 | x86_64 | OSS
i | yast2-ycp-ui-bindings | package | 4.6.0-1.3 | x86_64 | OSS
i+ | yast2-alternatives | package | 4.6.0-1.1 | x86_64 | OSS
i+ | yast2-bootloader | package | 4.6.2-1.1 | x86_64 | OSS
i+ | yast2-control-center-qt | package | 4.6.1-1.1 | x86_64 | OSS
i+ | yast2-sysconfig | package | 4.6.0-1.1 | noarch | OSS
Yast is working fine here.
they are installed yet !
i installed xcb package and it’s working now !
Solved !
1 Like
xcb package is completely unrelated to YaST2 or Qt platform plugin, I do not have it installed and all YaST2 modules work. Either you did something else or you installed some other package.
I did not anything else than to install xcb !
The error message is explicit, the needed plugin was xcb.
Running “sudo kdesu yast2” is redundant … next time, leave off “kdesu”
Look at my exact duplicate output if I run your command line - I have never had “xcb” installed, and yet, graphical Yast works!
I’ll hazard a guess … you installed xcb, but Yast / zypper included other required (missing) packages to install.
:~> sudo kdesu yast2
[sudo] password for root:
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
.
Do you even know what xcb does (it’s basically copy-n-paste)?
# zypper if --requires xcb
Loading repository data...
Reading installed packages...
Information for package xcb:
----------------------------
Repository : openSUSE-Tumbleweed-Oss
Name : xcb
Version : 2.5-203.13
Arch : x86_64
Vendor : openSUSE
Installed Size : 46.3 KiB
Installed : No
Status : not installed
Source package : xcb-2.5-203.13.src
Upstream URL : http://www.goof.com/pcg/marc/xcb.html
Summary : X11 cut&paste utility
Description :
Xcb provides access to the cut buffers built into every X server. It
allows the buffers to be manipulated either via the command line or
with the mouse in a point and click manner. The buffers can be used as
holding pens to store and retrieve arbitrary data fragments, so any
number of different pieces of data can be saved and recalled later. The
program is designed primarily for use with textual data.
Requires : [4]
libc.so.6(GLIBC_2.34)(64bit)
libX11.so.6()(64bit)
libXt.so.6()(64bit)
libXaw.so.7()(64bit)
.
sudo yast2 start in text mode and it was not the goal !
I’m not even sure what that means.
Keep in mind yast command is the text mode version.
And yast2 is the graphical version.
So if you run
sudo yast2
You will see the graphical version of Yast … without the xcb error.
After all, you demonstrated launching Yast from a CLI, and showed the error. ANYONE who runs your example of “sudo kdesu yast2” will see the SAME error, if they don’t have xcb. xcb is NOT required to get graphical Yast.
No, you won’t (with default settings). YaST2 will fail to open $DISPLAY and fail back to text version.
It happened because you over do your command (sudo kdesu yast2) which is not correct. 
You have to use:
su -c yast2 will prompt you for root pasword in the terminal then yast2 gui will run.
or
kdesu yast2 will launch a gui password promt then type password and yast2 gui will run.
2 Likes
Some folks use kdesu because it offers to save the password … and it really does save the password.
No idea why the OP tries to run “sudo kdesu yast2”. I just tried running that command string and I get the exact same xcb error (as another replier mentioned). I have no use for xcb … but I’ll run the sudo command properly 
All this discussion about sudo or not sudo with kdesu is nice, but does not change the fact that before to install xcb package, into yast2 launched from KDE GUI and not command line, the modules were not working.
After installed the xcb package, the modules worked.
May be you got lucky that when you install “xcb” it pulled some yast2 dependencies with it.
I don’t have xcb installed but yast2 is working as it should.
~> cnf xcb
The program 'xcb' can be found in the following package:
* xcb [ path: /usr/bin/xcb, repository: zypp (repo-oss) ]
Try installing with:
sudo zypper install xcb
means xcb is not installed here.
1 Like