Clean install Qt on a fresh Debian leads to problems with libqxcb.so.debug

[Inso]

Hi,

after running into critical issues installing mqtt library when using the debian package installer (see [https://forum.qt.io/topic/115350/installing-mqtt-library](this forum post)), I try now to install Qt using the online installer.
Base is "debian-10.4.0-amd64-xfce-CD-1.iso" installed as a VM (VMware Workstation 15). Set it up this morning (several times^^), only installed stuff is VMWareTools and Filezilla.

I now write detailed about the Qt installation, also add a Problem section below which just shows the problem:

The detailed Qt part:
according to
[https://doc-snapshots.qt.io/qt5-5.15/linux.html](this post)
I executed

sudo apt-get install build-essential libgl1-mesa-dev

Then I installed Qt from
[https://www.qt.io/download](the official source)
-> go open source
-> download online installer

first try:

chmod u+x qt-unified-linux-x64-3.2.3-online.run
./qt-unified-linux-x64-3.2.3-online.run
./qt-unified-linux-x64-3.2.3-online.run: error while loading shared libraries: libxkbcommon-x11.so.0: cannot open shared object file: No such file or directory

according to
[https://forum.qt.io/topic/99562/qt-5-12-1-cannot-load-library-opt-qt-5-12-1-gcc_64-plugins-platforms-libqxcb-so-libxkbcommon-x11-so-0-cannot-open-shared-object-file-no-such-file-or-directory/2](this post)
I executed

sudo apt install libxkbcommon-x11-0

Installed components:

strangely, "standard" does not choose a single component

After installation, I chose:

• "Qt Quick Application - empty"

• "Build-system: qmake"

• "min version: Qt 5.12"

• no language

among Kits, I chose
"Desktop Qt 15.5.0 GCC 64bit (default)".
Opening it shows no debugger, debugger page does no list one.
[https://doc.qt.io/qtcreator/creator-debugger-engines.html](this page)
mentions GDB as a native debugger

Installing debugger:
[http://www.gdbtutorial.com/tutorial/how-install-gdb](this page)
says commands to execute:

sudo apt-get update
sudo apt-get install gdb

which installs the debugger

after restarting QtCreator, the debugger shows up, but Qt-Version is greyed out:

however, as no error shows up, I create the project.

Here, without changing anything, just launching, I get the error

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.

according to [https://forum.qt.io/topic/93247/qt-qpa-plugin-could-not-load-the-qt-platform-plugin-xcb-in-even-though-it-was-found/2](this page)
I need to set QT_DEBUG_PLUGINS to 1 for more information, according to
[https://stackoverflow.com/questions/34379017/setting-qt-debug-plugins-fails](this page)
the command is

qputenv("QT_DEBUG_PLUGINS", QByteArray("1"));

when used in main cpp, executed first off.

PROBLEM:
now, end of the output shows:

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() looking at "/home/inso/Qt/5.15.0/gcc_64/plugins/platforms/libqxcb.so.debug"
"The shared library was not found." 
         not a plugin
QFactoryLoader::QFactoryLoader() checking directory path "/home/inso/build-untitled-Desktop_Qt_5_15_0_GCC_64bit-Debug/platforms" ...
Cannot load library /home/inso/Qt/5.15.0/gcc_64/plugins/platforms/libqxcb.so: (libxcb-icccm.so.4: Kann die Shared-Object-Datei nicht öffnen: Datei oder Verzeichnis nicht gefunden)
QLibraryPrivate::loadPlugin failed on "/home/inso/Qt/5.15.0/gcc_64/plugins/platforms/libqxcb.so" : "Cannot load library /home/inso/Qt/5.15.0/gcc_64/plugins/platforms/libqxcb.so: (libxcb-icccm.so.4: Kann die Shared-Object-Datei nicht öffnen: Datei oder Verzeichnis nicht gefunden)"
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, webgl, xcb

However, looking for the path returns the same one used by the compiler:

sudo find / -name libqxcb.so.debug
/home/inso/Qt/5.15.0/gcc_64/plugins/platforms/libqxcb.so.debug

it is here directly pointing me to the debug, which I installed later on. I have searched for "libqxcb.so.debug" here on the forum and online, but it does not appear somewhere.

Does anybody have an idea how to solve this. No matter reinstalling, downloading whatever. I´m working on this problems for ~two days now, every solution is appreciated which solves the problem. Only thing is, I´d like to stick to Debian, as later I also will reinstall my Pi same way then here, and be able to debug the application there.

[WayToGoPotato]

I have been struggling with the same exact problem for days as well. The interesting part is the named missing shared library (libqxcb.so.debug) is available in the same directory that printed in the error message.
I installed all the recommended libraries listed in: https://doc.qt.io/qt-5/linux-requirements.html and I still have the same error message.

[kshegunov]

Post the plugin diagnostics please. Also, judging by the message you need to install libxcb-icccm4.

[Talkless]

"xcb" plugin error seems similar to:
https://bugreports.qt.io/browse/QTBUG-88688

Creating symlink /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 -> /usr/lib/x86_64-linux-gnu/libxcb-util.so.0 might help?