solved: Could not load the Qt platform plugin "xcb"

[ljubomirb]

I will leave here solution for a problem that I could not fix for days, hope it would help someone:
So, the error was:

QObject::moveToThread: Current thread (...) is not the object's thread (...).
Cannot move to target thread (...)
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/(...)site-packages/cv2/qt/plugins" 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.

I was trying hard, but could not fix it. I was downloading literally hundreds of different packages, over and over again, trying all sorts of "hacks" found online, eventually trying anaconda, a massive download...
In the end, I don't know if that was the fix, because my system is about to be reinstalled after all of my "trying", BUT, after I wrote this in console:
export QT_QPA_PLATFORM=offscreen
everything worked.
Again, don't know if this was solution OR any of hundreds of packages installed, but try this first. If it works, maybe add this to Q&A .
Good luck!

[Tom94]

Hi there, thanks for reporting. This seems to have been a problem with the cv2 Python package and how it loops in Qt -- the instant-ngp codebase itself doesn't actually use Qt anywhere. Cheers!

[Ednaordinary]

Not sure exactly why, but this made it work for me! original error was

`qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/usr/local/lib/python3.9/dist-packages/opencv_python-4.5.5.64-py3.9-linux-x86_64.egg/cv2/qt/plugins" 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: xcb, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc.`

I agree this should be added to the Q&A, even if its a dependency and not instant-ngp that is causing trouble

[ben-milanko]

I ran into this issue, it seems to be from open-cv opencv/opencv-python#46.

Using open-cv-python-headless instead seems to work for me: https://stackoverflow.com/a/72090539

pip uninstall opencv-python
pip install opencv-python-headless

[BoZhiStudying233]

@abnormal749 I met the same problem. Have you solved it? I solved this problem by isolating the two programs via a virtual environment.

[joyehsu]

Works for me too, thanks very much~
My system is Win10 + WSL2

[guliqianxun]

For me, this causing I use vscode connect to host, and no screen to show. I use realVNC connect the host and run the testing code there is no error then.

[Aut6ot]

Thank you! This helped a lot

[Twograpefruit]

Thank you very much, the path I reported the error did contain cv2'qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/anxing/.local/lib/python3.8/site-packages/cv2/qt/plugins"', and I successfully solved it.

[MashyBasker]

Hi, were you using a virtual environment for installing python packages? I was facing the exact same problem and 30 mins later I realized my virtual environment was not activated.

[hoods-py]

i am using a virtual environment
and i'm having the same issue

[yojetsharma]

I am trying to run rstudio in a conda environment on an institutional server and I am getting the following error:

(rstudio) [yojetsharma@pakeeza ~]$ rstudio
TTY detected. Printing informational message about logging configuration. Logging configuration loaded from '/etc/rstudio/logging.conf'. Logging to '/home/praghu/yojetsharma/.local/share/rstudio/log/rdesktop.log'.
No protocol specified
Fontconfig warning: ignoring UTF-8: not a valid region tag
WebEngineContext used before QtWebEngine::initialize() or OpenGL context creation failed.
This plugin does not support propagateSizeHints()
This plugin does not support raise()
Failed to create OpenGL context for format QSurfaceFormat(version 2.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::DefaultSwapBehavior, swapInterval 1, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::NoProfile) 
Aborted
[5851:5851:0100/000000.063786:ERROR:zygote_linux.cc(607)] Zygote could not fork: process_type renderer numfds 3 child_pid -1
[5851:5851:0100/000000.063868:ERROR:zygote_linux.cc(639)] write: Broken pipe (32)

[kassbohm]

Worked also for me on Linux Mint.

[Kupofty]

Also worked for me on Ubuntu20 after the last update of QtCreator, thanks a lot !

[montanaviking]

running Ubuntu 22.04. Sadly installing opencv-python-headless did not work for me

[The-R4V3N]

Thanks this finally worked

[fattypiggy]

This one works for me, thanks a lot.

[israelins85]

To solve this just run:

sudo apt-get install libxcb-xinerama0

[ArunChamiyappan]

The same here, Thank you

[Lijuming33]

ubuntu 2204，有用！

[xyf9474]

牛逼

[ll553664391]

works for me . on ubunut 20.04

[Joan-Hou]

To solve this just run:

sudo apt-get install libxcb-xinerama0

very helpful! worked for me! I am using ubuntu20.04, windows10, wsl1, on conda enviroment.

[Jalagarto]

https://stackoverflow.com/a/68058308/9033534 - first answer

for pyqt6 in ubuntu 20.04, following spell in forum linked above, solved the problem for me sudo apt-get install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev libxkbcommon-dev libxkbcommon-x11-dev
Author: harish
Oct 21, 2021

[criogenox]

It works!!!! Thanks, my friend.

[Drone944]

Thanks Bro, it works, saved me a lot of time.

[interval1066]

Thanks Jalagarto, your apt install chain worked for me as well. I know a lot of AI tools as well as everything else uses python, it seems, but I resent having to install a bunch of junk I don't use just to get qtcreator working. I didn't ask the updater to install this copilot client on my qt stack.. especially anything made with python. I really resent this.

[mahdi3100]

thanks mate

[zezar98]

It worked for me thanks! I just installed Debian 12.5 and anaconda-navigator wasn't working for me. After install those packages it worked.

[tomnattle]

sudo apt-get install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev libxkbcommon-dev libxkbcommon-x11-dev

this work for me , i use qt in docker

[JoshuaTokisaki]

This worked for me: ubuntu 22.04 WSL 2

[jinhoishere]

This worked for me : Ubuntu WSL 2 22.04.4 LTS

[zym198098]

我用wsl2 ubuntu 22.04 有用。多谢

[Wangchangcong]

This worked for me : wsl1 ubuntu 20.04

[pporwal015]

Thanks. Worked for me on WSL ubuntu

[bhjolly]

export QT_QPA_PLATFORM=offscreen

I ran across this thread trying to diagnose the same issue trying to run Agisoft Metashape on a GPU-equipped-but-headless server. Exporting that environment variable fixed it.

[BryceWayne]

This worked Ubuntu+WSL+Conda+Python3.10

[AmrinKareem]

This worked for me in Linux with conda environment. Thank you!

[m1ndcrash]

Oh my god. 4 hours. This one saved me. PS training nerf

[J1ungle]

This works for ubuntu 20.04 in docker!

[lykuan]

wsl2 not work for me , why?

[Petros626]

My solutions I've tested on my code.

If you get Could not load the Qt platform plugin "xcb"after import cv2
fix 1: use os.environ.pop("QT_QPA_PLATFORM_PLUGIN_PATH") in code
fix 2: try pip install opencv-python-headless (without GUI)
fix 3: delete the libqxcb from "/home/usernamexyz/.local/lib/python3.9/site-packages/cv2/qt/plugins/platforms

[HasarinduPerera]

Thanks, this is useful indeed!

[DatleUNL]

Fix 1 worked for my Kinz library that uses opencv-contrib-python. Thanks!

[WEIIEW97]

Fix 1 solved mine. Thanks a lot!

[yaioqin]

fix 3 is useful. Thanks

[wh1t3h47]

thank you

[masuraoru]

In my case it was conflict in Qt installation on the system with the Qt that is shipped with OpenCV. Solved on Ubuntu 22.04 Desktop by removing opencv-python:
pip3 uninstall opencv-python
and reinstaing with --no-binary option:
pip3 install --no-binary opencv-python opencv-python
Warning: opencv-python compiling may take some time.

[AnshuDFKI]

This is the only solution which worked for me. Thank You

[xmlyqing00]

This is the most decent way to solve this problem.

[abnormal749]

It's the only solution really helps for my program with qt and cv.imshow

[Lwy-1998]

This is really help！！！

[JasOleander]

You saved my day. This is the only answer for both qt and cv2 errors.
Thank you so much. :)

[ljjTYJR]

My problem:

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, xcb.

I use the command:

export DISPLAY=:0

works for me...

[eneserdo]

Worked for WSL, thanks

[tymho]

Worked for me! I think this might be related to SSH?

[kelogs]

SSH

Sure thing, no display through SSH sessions!

[Soka21]

This worked for me too, thanks!

[beizhengren]

SSH

Sure thing, no display through SSH sessions!
hey bro, have you solved it in ssh?

[trojanof]

Thanks for solution! export QT_QPA_PLATFORM=offscreen works for me! I had an issue running streamlit app on a server with ubuntu and music21 python module. I had musescore installed there but faced the qt related problem when trying to display music scores. Setting that variable solved my problem.

[opticalor]

Thats not work,but i use export QT_QPA_PLATFORM_PLUGIN_PATH=/path/to/your/qt/directory/plugins,is run now.(dont forget unset QT_QPA_PLATFORM if you accept before this)

[zzhuolun]

I found this answer that showed how to narrow down and locate the problem very helpful.

In my case, installing the specific missing libraries AND reinstalling PyQt5 solved the problem.

[Truthuleave]

No error appears through export QT_DEBUG_PLUGINS=1 when in conda venv.
Quitting from conda venv works for me~

[leung1010]

I will leave here solution for a problem that I could not fix for days, hope it would help someone: So, the error was:

QObject::moveToThread: Current thread (...) is not the object's thread (...).
Cannot move to target thread (...)
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/(...)site-packages/cv2/qt/plugins" 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.

I was trying hard, but could not fix it. I was downloading literally hundreds of different packages, over and over again, trying all sorts of "hacks" found online, eventually trying anaconda, a massive download... In the end, I don't know if that was the fix, because my system is about to be reinstalled after all of my "trying", BUT, after I wrote this in console: export QT_QPA_PLATFORM=offscreen everything worked. Again, don't know if this was solution OR any of hundreds of packages installed, but try this first. If it works, maybe add this to Q&A . Good luck!

This answer just turns off the screen. Maybe this cmd could help you guys fix the issue. sudo apt install libxcb-xinerama0

[sajadalipour]

It works for me after installing opencv-contrib-python-headless

[1850298154]

您的邮件已收到！祝工作顺利！

[eavelardev]

export XDG_CURRENT_DESKTOP=Unity could work for Ubuntu, but I have an undesired behavior where PyQt windows and dialogs aren't centered

[CrikersPL]

flatpak override --user --env=QT_QPA_PLATFORM=wayland org.kde.dolphin
(org.kde.dolphin) in my case

Worked for me

[stevenlafl]

I got this error when loading a QT6 program that didn't ship the required QT6 plugins. In particular, obs under rockchip repository for aarch64. Instead, the plugin package installed was a QT5 one, so essentially it wouldn't find any DDE plugins.

apt-get install qt6-qpa-plugins

will install the libqxcb.so file required along with libqeglfs.so, libqminimalegl.so, libqoffscreen.so, libqvnc.so, libqlinuxfb.so, libqminimal.so and libqvkkhrdisplay.so.

[AndrewHart1]

1.7.9
Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
QObject::moveToThread: Current thread (0x1f63490) is not the object's thread (0x2de7af0).
Cannot move to target thread (0x1f63490)

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/smart-daq/anaconda3/lib/python3.9/site-packages/cv2/qt/plugins" 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: xcb, eglfs, minimal, minimalegl, offscreen, vnc, webgl.

Aborted (core dumped)

i am getting this error and after trying all the aformentioned methods it is still not working. does anyone have any ideas

[Franciscofmv]

Thanks for posting this! ENV QT_QPA_PLATFORM=offscreen in the Dockerfile solved it for me when building a docker container. I was trying to run PyQt5 in a container but I was having that error. Thanks again! Note: I first needed to do RUN chmod -R 777 /opt/miniconda3; yum -y install mesa-libGL in the Dockerfile to install the graphic library.

[Abbsalehi]

This worked for me.

sudo apt-get install libx11-xcb1 libxcb1 libxcb-glx0 \
libxcb-keysyms1 libxcb-image0 libxcb-shm0 libxcb-icccm4 \
libxcb-sync1 libxcb-xfixes0 libxcb-shape0 libxcb-randr0 \
libxcb-render-util0 libxcb-render0 libxcb-xinerama0 libxcb-xkb1 libxkbcommon-x11-0

[space-pixel]

When I tried these solutions on windows 10 while using a container the code compiled but did not output the visual. The fix I found was installing Xming here: https://sourceforge.net/projects/xming/ and using this line: docker run -e DISPLAY=host.docker.internal:0.0 your-qt-app to run the container.

[johndpope]

conda install -c conda-forge qt

[santo4ul]

sudo apt-get remove libxcb-xinerama0
sudo apt-get install libxcb-xinerama0

This works for me. Hope this helps someone.

[IgdaliasCabamba]

sudo dnf install qt5-qtbase-devel Worked for me on Fedora 40 with xfce

[JLee2022]

I fixed it by sudo apt-get remove libxcb-xinerama0 sudo apt-get install libxcb-xinerama0.
and I set export QT_QPA_PLATFORM=xcb.
Notice that i am using vscode to debug python files.

[JLee2022]

I found that i need to run the code in terminal. Than I can run it in my vscode. strange...