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

trimixotun

It's looks slightly outdated, but maybe it someone helps:

Debian 10 x86-64.
LXDE
Fresh net install Qt 5.12.10

Qtcreator first launch problem: "qt.qpa.plugin: Could not load the Qt platform plugin "xcb"".

Nothing from above helps at all. Qtcreator needs libxcb-util.so.1, but system has only libxcb-util.so.

Simple solution:

sudo ln -s /usr/lib/x86_64-linux-gnu/libxcb-util.so /usr/lib/x86_64-linux-gnu/libxcb-util.so.1

All work, folks.

wobl

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

sudo ln -s /usr/lib/x86_64-linux-gnu/libxcb-util.so /usr/lib/x86_64-linux-gnu/libxcb-util.so.1

Thanks a lot ... this is working for MX Linux too - but with a little correction:

sudo ln -s /usr/lib/x86_64-linux-gnu/libxcb-util.so.0.0.0 /usr/lib/x86_64-linux-gnu/libxcb-util.so.1

nileshmoodley

@Srinivas-Reddy Thank you very much - this solved it for me!

Jean-Noel

For me (on Debian), the only thing that worked was to completely uninstall Qt with Maintenance Tool, and install with "default" configuration.

ajlogo

The plugin problem started when I re-created an Anaconda env (PyQt5 and ubuntu) from a .yml file.
https://newini.wordpress.com/2020/08/13/how-to-solve-xcb-plugin-error-in-pyqt5/
Had the working answer for me:
sudo apt-get install qt5-default # For Ubuntu system

pixel_08

@SGaist hi,
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.
/bin/bash: line 133: 1745 Aborted (core dumped) python csv2txt.py

Then I added, export QT_DEBUG_PLUGINS=1
got error as,
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/bin/platforms" ...
Cannot load library /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so: (libxcb-util.so.1: cannot open shared object file: No such file or directory)
QLibraryPrivate::loadPlugin failed on "/builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so" : "Cannot load library /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so: (libxcb-util.so.1: cannot open shared object file: No such file or directory)"

and ran ldd /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so

linux-vdso.so.1 (0x00007ffc728e9000)
libQt5XcbQpa.so.5 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libQt5XcbQpa.so.5 (0x00007fda88aa2000)
libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007fda88a50000)
libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007fda88994000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fda88776000)
libQt5Gui.so.5 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libQt5Gui.so.5 (0x00007fda87e45000)
libQt5DBus.so.5 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libQt5DBus.so.5 (0x00007fda87bb7000)
libQt5Core.so.5 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libQt5Core.so.5 (0x00007fda873c1000)
libGL.so.1 => /usr/lib/x86_64-linux-gnu/libGL.so.1 (0x00007fda8732d000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fda8730c000)
libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007fda87307000)
libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007fda87300000)
libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007fda870f9000)
libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007fda870f4000)
libxcb-util.so.1 => not found
libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007fda86ef1000)
libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007fda86edf000)
libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007fda86cdb000)
libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007fda86cca000)
libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007fda86cc5000)
libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007fda86cbb000)
libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007fda86cb1000)
libxcb-xinerama.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinerama.so.0 (0x00007fda86cac000)
libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007fda86c8e000)
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fda86c62000)
libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007fda86a50000)
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007fda8690f000)
libxkbcommon-x11.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007fda86904000)
libxkbcommon.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007fda868c2000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fda868bd000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fda86737000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fda865b4000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fda8659a000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fda863d9000)
libxcb-util.so.1 => not found
libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fda863d4000)
libglib-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fda862b3000)
libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007fda86276000)
libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007fda8626d000)
libpng16.so.16 => /usr/lib/x86_64-linux-gnu/libpng16.so.16 (0x00007fda86234000)
libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007fda861e1000)
libicui18n.so.56 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libicui18n.so.56 (0x00007fda85d46000)
libicuuc.so.56 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libicuuc.so.56 (0x00007fda8598e000)
libicudata.so.56 => /builds/sravani_detect/video_frames/venv/lib/python3.9/site-packages/PyQt5/Qt5/plugins/platforms/../../lib/libicudata.so.56 (0x00007fda83fab000)
/lib64/ld-linux-x86-64.so.2 (0x00007fda89001000)
libGLX.so.0 => /usr/lib/x86_64-linux-gnu/libGLX.so.0 (0x00007fda83f77000)
libGLdispatch.so.0 => /usr/lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007fda83eba000)
libxcb-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.0 (0x00007fda83cb1000)
libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007fda83aad000)
libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fda838a7000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fda83833000)
libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007fda83790000)
libbsd.so.0 => /usr/lib/x86_64-linux-gnu/libbsd.so.0 (0x00007fda83776000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fda8376c000)
liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007fda83744000)
liblz4.so.1 => /usr/lib/x86_64-linux-gnu/liblz4.so.1 (0x00007fda83725000)
libgcrypt.so.20 => /lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007fda83607000)
libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007fda835e2000)

what to do next?
Thank you!

SGaist

Install the package that provides "libxcb-util.so.1" on your system.

pixel_08

@SGaist
Thank you, Can we run PyQt5 applications in gitlab by setting up a pipeline?
Please clarify this.

SGaist

Do you mean run tests on your GUI in GitLab ?

pixel_08

@SGaist yes

SGaist

Yes you can, you have to use the offscreen backend though unless your runner provides adequate connection to an X server.

Srinivas Reddy

@Srinivas-Reddy This worked for me. Thank you.

steel357

@jarvis Hi jarvis,
I am also getting same problem
Got keys from plugin meta data ("webgl")
QFactoryLoader::QFactoryLoader() looking at "/home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so"
Found metadata in lib /home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"archreq": 0,
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/bin/platforms" ...
loaded library "/home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so"
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.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl, xcb.

Aborted (core dumped)

did u found the solution??

I am using Linux in windows(WSL)

steel357

@SGaist
@jarvis Hi guys,
I am also getting the same problem

Got keys from plugin meta data ("webgl")
QFactoryLoader::QFactoryLoader() looking at "/home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so"
Found metadata in lib /home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"archreq": 0,
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 331520
}

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/bin/platforms" ...
loaded library "/home/vineeth/.local/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms/libqxcb.so"
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.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl, xcb.

Aborted (core dumped)

**did u found the solution??

I am using Linux in windows(WSL) and tried it normal ubuntu also getting same error**

SGaist

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

You should check the Windows documentation.

MBat

Good morning,

I am having trouble running a python code (not written by me) that uses pyroot.
My working system is Ubuntu 18.

At the start of the script I get the following message

cling::DynamicLibraryManager::loadLibrary(): /home/matteo/anaconda3/bin/../lib/libfontconfig.so.1: undefined symbol: FT_Done_MM_Var
Error in TInterpreter::TCling::AutoLoad: failure loading library libGX11TTF.so for TGX11TTF
cling::DynamicLibraryManager::loadLibrary(): /home/matteo/anaconda3/bin/../lib/libfontconfig.so.1: undefined symbol: FT_Done_MM_Var
Info in TApplication::InitializeGraphics: no TTF support

While, at the end, just before it crushes, (after export QT_DEBUG_PLUGINS=1) I get the following

QFactoryLoader::QFactoryLoader() checking directory path "/home/matteo/anaconda3/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqeglfs.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqeglfs.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"eglfs"
]
},
"archreq": 0,
"className": "QEglFSIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqminimal.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqminimal.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 0,
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqminimalegl.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqminimalegl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimalegl"
]
},
"archreq": 0,
"className": "QMinimalEglIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqoffscreen.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqoffscreen.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqvnc.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqvnc.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"vnc"
]
},
"archreq": 0,
"className": "QVncIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqwebgl.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqwebgl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"webgl"
]
},
"archreq": 0,
"className": "QWebGLIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("webgl")
QFactoryLoader::QFactoryLoader() looking at "/home/matteo/anaconda3/plugins/platforms/libqxcb.so"
Found metadata in lib /home/matteo/anaconda3/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"archreq": 0,
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 330752
}

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/matteo/anaconda3/bin/platforms" ...
Cannot load library /home/matteo/anaconda3/plugins/platforms/libqxcb.so: (/home/matteo/anaconda3/plugins/platforms/../../lib/libfontconfig.so.1: undefined symbol: FT_Done_MM_Var)
QLibraryPrivate::loadPlugin failed on "/home/matteo/anaconda3/plugins/platforms/libqxcb.so" : "Cannot load library /home/matteo/anaconda3/plugins/platforms/libqxcb.so: (/home/matteo/anaconda3/plugins/platforms/../../lib/libfontconfig.so.1: undefined symbol: FT_Done_MM_Var)"
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, minimal, minimalegl, offscreen, vnc, webgl, xcb.

The output of the command ls -l /usr/lib/x86_64-linux-gnu/libQt5Xcb* is

-rw-r--r-- 1 root root 1602 feb 7 2020 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.prl
lrwxrwxrwx 1 root root 21 feb 7 2020 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so -> libQt5XcbQpa.so.5.9.5
lrwxrwxrwx 1 root root 21 feb 7 2020 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 -> libQt5XcbQpa.so.5.9.5
lrwxrwxrwx 1 root root 21 feb 7 2020 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.9 -> libQt5XcbQpa.so.5.9.5
-rw-r--r-- 1 root root 1070840 feb 7 2020 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.9.5

So, the point is that I do not have a deep knowledge of Ubuntu system in genreal, and I do not know if the problem is only with QT plugins or is elsewhere. The only thing I know is that the code itself is working fine in other machines, so the problem should not rely there.

Thanks if you can help me, let me know if you need any other information.

Thanks!

SGaist

Hi and welcome to devnet,

Your anaconda installation looks unusual, how did you do it ?

MBat

Thanks for the welcome!

I actually don't remember anything particular from the installation of Anaconda. But it has been 3 years ago, so I might have forgotten.
Why do you say that it looks unusual?

SGaist

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

anaconda3/plugins/platforms/libqxcb.so

Usually conda environments are not located at that level. That's what I find suspicious. But I have essentially used miniconda rather than the full Anaconda.

Your main issue is that there's something wrong with your libfontconfig library.

Violet Giraffe

@Matriarch, thank you,

sudo apt-get install libxcb-xinerama0

worked for me on Ubuntu 20.04. Shame one has to scroll so deep down into the discussion before finding the answer.

Also, I recently spent a lot of time getting a Qt application to run in a Github Actions VM - I was battling the xcb errors. Here's the complete list of things that needed to be installed:

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