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

[JonB]

@mywings19 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

There's no error message until I closed the software.

In that case when does the message you showed earlier:

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/home/sugon/Software/Qt6.3.1/plugins/platforms/"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: linuxfb, minimal, offscreen, vnc.

appear? Not until after you close Creator? Interesting.....

[mywings19]

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

@mywings19 said in qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.:

There's no error message until I closed the software.

In that case when does the message you showed earlier:

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/home/sugon/Software/Qt6.3.1/plugins/platforms/"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: linuxfb, minimal, offscreen, vnc.

appear? Not until after you close Creator? Interesting.....

This 3 line message is showed when I build and run a test project.
I mean after I set QT_DEBUG_PLUGINS to 1, There's no extra error message except this 3 line when I start qtcreator or run project in terminal.

Now, I've uninstall the Qt and qtcreator,then installing by online installer.

[SGaist]

Is that a custom Qt build ? Because from the looks of it, the plugin is indeed not there.

[BenyaminZojaji]

In my case, I just upgrade PyQt5 to PyQt6 and that works.

[GEZawaTT]

@trimixotun this worked!! Thank you so much!

[3mad]

In my case, I had the issue when installing ParaView, things fixed by installing the libxcb-xinput0 package:
sudo apt-get install libxcb-xinput0

Then, things work fine.

[roux.benoit]

Hi,

I know this is an old post, but I have the same issue that comes up when I'm setting some path for the LD_Library_path.

for the context i'm creating a container that run an app with a gui using pyqt5, which works perfectly.

However, I also need to install matlab runtime and after I set up Matlab runtime environement path :

LD_LIBRARY_PATH=/opt/mscr/v912/runtime/glnxa64:/opt/mcr/v912/bin/glnxa64:/opt/mcr/v912/sys/os/glnxa64:/opt/mcr/v912/sys/opengl/lib/glnxa64

the gui stops working and I get the "qt.qpa.plugin ..." error message.

Any thoughts?
Thanks a lot

[SGaist]

@roux-benoit hi,

Check whether there's Qt libraries in your matlab installation.

[phil-lipp]

I hope someone on this forum can help me. I'm trying to use Howdy (https://github.com/boltgolt/howdy), but I get the error described by OP.
I only get the error when I use su -, however when I use plain su (without the -) it works. So I think i somehow messed up the install when I forgot to add the -... how can I fix this?

the error:

qt.qpa.xcb: could not connect to display 
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.
``

[JonB]

@phil-lipp
https://forum.qt.io/post/763171 was just asked.

[MarsOnMart]

I had too problems with this file.
It just depends from which shared file left you.
first at all set in the console :

export QT_DEBUG_PLUGINS=1

This will show you in which part it fails, normally is in libqxcb.so,

example:
python main.py

qt.core.plugin.factoryloader: checking directory path "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms" ...
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-generic.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-generic.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland"
        ]
    },
    "archlevel": 1,
    "className": "QWaylandIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimal.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "archlevel": 1,
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimal")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqeglfs.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "archlevel": 1,
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("eglfs")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-egl.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqwayland-egl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-egl"
        ]
    },
    "archlevel": 1,
    "className": "QWaylandEglPlatformIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland-egl")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqoffscreen.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "archlevel": 1,
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("offscreen")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqlinuxfb.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqlinuxfb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "linuxfb"
        ]
    },
    "archlevel": 1,
    "className": "QLinuxFbIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("linuxfb")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvnc.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "archlevel": 1,
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vnc")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvkkhrdisplay.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqvkkhrdisplay.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vkkhrdisplay"
        ]
    },
    "archlevel": 1,
    "className": "QVkKhrDisplayIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("vkkhrdisplay")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimalegl.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "archlevel": 1,
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimalegl")
qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so"
qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archlevel": 1,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 394496
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("xcb")
qt.core.plugin.factoryloader: checking directory path "/usr/bin/platforms" ...
qt.core.library: "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)"
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: wayland, minimal, eglfs, wayland-egl, offscreen, linuxfb, vnc, vkkhrdisplay, minimalegl, xcb.

zsh: IOT instruction  python main.py

And this error occurs when some of the shared libraries are not found.
In my case was the :
"/usr/bin/platforms" ...
qt.core.library: "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so:

== =>(libxcb-cursor.so.0: cannot open shared object file: No such file or directory) <===

qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: cannot open shared object file: No such file or directory)"
.
This is the shared library that lefts , it could that does not be the only one , so for see better which shared libraries are and which not use the next command :

ldd : /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so

This must show you the next thing :

::
ldd: ./:: No such file or directory
/home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/libqxcb.so:
        linux-vdso.so.1 (0x00007fff8b5b6000)
        libQt6XcbQpa.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6XcbQpa.so.6 (0x00007febd8bec000)
        libxkbcommon-x11.so.0 => /lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007febd8bc3000)
        libxkbcommon.so.0 => /lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007febd8b7d000)
        libxcb-cursor.so.0 => not found
        libxcb-icccm.so.4 => /lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007febd8b76000)
        libxcb-image.so.0 => /lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007febd8b6e000)
        libxcb-keysyms.so.1 => /lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007febd8800000)
        libxcb-randr.so.0 => /lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007febd8b5d000)
        libxcb-render-util.so.0 => /lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007febd8400000)
        libxcb-shm.so.0 => /lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007febd8b58000)
        libxcb-sync.so.1 => /lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007febd8b50000)
        libxcb-xfixes.so.0 => /lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007febd8b45000)
        libxcb-render.so.0 => /lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007febd8b37000)
        libxcb-shape.so.0 => /lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007febd8b32000)
        libxcb-xkb.so.1 => /lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007febd8b15000)
        libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1 (0x00007febd8aeb000)
        libQt6OpenGL.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6OpenGL.so.6 (0x00007febd8a4a000)
        libQt6Gui.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007febd7a00000)
        libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007febd8779000)
        libQt6Core.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007febd7200000)
        libX11-xcb.so.1 => /lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007febd8a43000)
        libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007febd8637000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007febd8a3c000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007febd8a37000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007febd6e00000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007febd7921000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007febd8a17000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007febd701f000)
        libxcb-cursor.so.0 => not found
        libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007febd6cbd000)
        libgthread-2.0.so.0 => /lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007febd8a10000)
        libxcb-util.so.1 => /lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007febd8a08000)
        libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6 (0x00007febd8a03000)
        libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007febd6a00000)
        libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007febd861f000)
        libfontconfig.so.1 => /lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007febd78d6000)
        libQt6DBus.so.6 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007febd693b000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007febd83e1000)
        libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007febd6870000)
        libGLdispatch.so.0 => /lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007febd67b7000)
        libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007febd78a2000)
        libicui18n.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicui18n.so.56 (0x00007febd6200000)
        libicuuc.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicuuc.so.56 (0x00007febd5e00000)
        libicudata.so.56 => /home/user/.local/lib/python3.11/site-packages/PySide6/Qt/plugins/platforms/../../lib/libicudata.so.56 (0x00007febd4400000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007febd8616000)
        /lib64/ld-linux-x86-64.so.2 (0x00007febd8ca7000)
        libpcre2-8.so.0 => /lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007febd6c23000)
        libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007febd83cb000)
        libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007febd678c000)
        libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007febd6736000)
        libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16 (0x00007febd6700000)
        libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007febd8607000)
        libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x00007febd7895000)
        libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007febd4331000)
        libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007febd66dd000)
        libcap.so.2 => /lib/x86_64-linux-gnu/libcap.so.2 (0x00007febd6c17000)
        libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007febd41ea000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007febd66ae000)
        libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007febd412e000)
        liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007febd61da000)
        libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007febd4106000)

As you can see the shared library which is not , appears like not found

    libxcb-cursor.so.0 => not found

Just thus easier to fix it , is using :

sudo apt install libxcb-cursor0

In your case could be another like: libxcb-randr0

[IuriiV]

@twar Hi, solved by sudo apt-get install libxcb*

[fokhagyma]

@IuriiV Thank you, it solved for me too.

[booter]

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: offscreen, wayland, vnc, minimalegl, xcb, wayland-egl, eglfs, linuxfb, vkkhrdisplay, minimal.

sudo apt-get install libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev libxcb-shape0-dev libxcb-xkb-dev

sudo apt-get install libxkbcommon-x11-dev

sudo apt-get install libxcb-xinerama0

++++++++++++++++++++++++++++++++++

sudo apt-get install -qq libglu1-mesa-dev libx11-xcb-dev '^libxcb*'

[jsulm]

@booter As in your other thread: do you have a question? Please ask a clear question if you have one!
If you have same issue as in this thread then the solution should also be same: did you do that?

[Spiv]

@jsulm
Since I am getting the same error, I read the whole thread from the very beginning and tried all solutions but I still cannot load something....
I have Lenovo Ideapad Flex5 running Kubuntu.
I upgraded Kubuntu 20.04 first to 23.04,then to 23.10.
Then something happened ...
Now when I start the laptop I get to the login, put my password, the desktop and wallpaper show for 1 second, then I get a black screen.
Using Ctrl+Alt+F4 I can get to a terminal, but a cannot copy/paste anything into a browser since I cannot load a browser because I get an error very similar to the original post.
I am writing this through my phone.
I can take pictures of the terminal and the result of commands, but cannot paste anything....
Can you help me please regain my desktop display?

BTW, how do I attach pictures here?

[SGaist]

@Spiv hi and welcome to devnet,

Did you try to use the Wayland session rather than the Xorg ? You should be able to select that from the login screen.

[Spiv]

@SGaist
Hi, thank you for responding so quickly.
I don't know what you are suggesting, sorry....
How do I select a different (Wayland) session?

[Spiv]

I did figure that out...
With 'Plasma Wayland' I did not even see a flash of my desktop, just a dark screen.
'Plasma X11', desktop flash for a second, then black screen.
'Ubuntu' gave me a blue screen on which I can invoke all applications, including Firefox.
'Ubuntu Wayland' and 'Ubuntu on Xorg' also give me a working environment.
However, I cannot go into 'settings' for some reason.

[SGaist]

Did you check the logs of your system to see if something else is wrong ?

In any case, I would also check with the Kubuntu folks.