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Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found"

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  • H Hikari Tretaki

    @lvlanson I had the same problem. You can install headless opencv without GUI. Then it works.

    pip install opencv-python-headless

    R Offline
    R Offline
    Rainerino
    wrote on last edited by
    #9

    @Hikari-Tretaki Thank you very much! Your solution work for me too!

    1 Reply Last reply
    0
    • M Offline
      M Offline
      michwil99
      wrote on last edited by
      #10

      @Hikari-Tretaki thank you very much!!

      1 Reply Last reply
      0
      • Y Offline
        Y Offline
        yashwant
        wrote on last edited by
        #11

        Hi, The error still persists even when I use "pip install opencv-python-headless"

        Error message:
        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, minimal, minimalegl, offscreen, vnc, webgl, xcb.

        /opt/conda/envs/yashenv2/.tmp8gb_phfb: line 3: 17 Aborted python TAD_GUI_Contoller.py
        ERROR conda.cli.main_run:execute(33): Subprocess for 'conda run ['python', 'TAD_GUI_Contoller.py']' command failed. (See above for error)

        Other info: When I used opencv-python (Error was similar like above except it had - Could not load the Qt platform plugin "xcb" in ".../python3.7/site-packages/cv2/qt/plugins" even though it was found.). I am using docker (with Ubuntu 18 + WSL2). The problem persist only in docker container. (The python codes work fine in windows)

        Am I missing some Ubuntu libraries? I tried installing libxcb's and many other libraries. It just does not work. Or is it related to PyQt5?

        jsulmJ Pablo J. RoginaP 2 Replies Last reply
        0
        • Y yashwant

          Hi, The error still persists even when I use "pip install opencv-python-headless"

          Error message:
          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, minimal, minimalegl, offscreen, vnc, webgl, xcb.

          /opt/conda/envs/yashenv2/.tmp8gb_phfb: line 3: 17 Aborted python TAD_GUI_Contoller.py
          ERROR conda.cli.main_run:execute(33): Subprocess for 'conda run ['python', 'TAD_GUI_Contoller.py']' command failed. (See above for error)

          Other info: When I used opencv-python (Error was similar like above except it had - Could not load the Qt platform plugin "xcb" in ".../python3.7/site-packages/cv2/qt/plugins" even though it was found.). I am using docker (with Ubuntu 18 + WSL2). The problem persist only in docker container. (The python codes work fine in windows)

          Am I missing some Ubuntu libraries? I tried installing libxcb's and many other libraries. It just does not work. Or is it related to PyQt5?

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #12

          @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

          Am I missing some Ubuntu libraries?

          Yes.
          Set QT_DEBUG_PLUGINS before starting the app and check output.

          https://forum.qt.io/topic/113070/qt-code-of-conduct

          1 Reply Last reply
          0
          • Y Offline
            Y Offline
            yashwant
            wrote on last edited by
            #13

            @jsulm said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

            Set QT_DEBUG_PLUGINS

            Can you tell me how can I set "export QT_DEBUG_PLUGINS =1" in docker container? Should it be written inside Dockerfile? or should I run the container something like docker run -it Image -v export QT_DEBUG_PLUGINS =1 ? or should I be using docker exec ?

            jsulmJ 1 Reply Last reply
            0
            • Y yashwant

              @jsulm said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

              Set QT_DEBUG_PLUGINS

              Can you tell me how can I set "export QT_DEBUG_PLUGINS =1" in docker container? Should it be written inside Dockerfile? or should I run the container something like docker run -it Image -v export QT_DEBUG_PLUGINS =1 ? or should I be using docker exec ?

              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #14

              @yashwant That I don't know, sorry.

              https://forum.qt.io/topic/113070/qt-code-of-conduct

              1 Reply Last reply
              0
              • Y Offline
                Y Offline
                yashwant
                wrote on last edited by
                #15

                ok :( any thanks!

                1 Reply Last reply
                0
                • Y yashwant

                  Hi, The error still persists even when I use "pip install opencv-python-headless"

                  Error message:
                  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, minimal, minimalegl, offscreen, vnc, webgl, xcb.

                  /opt/conda/envs/yashenv2/.tmp8gb_phfb: line 3: 17 Aborted python TAD_GUI_Contoller.py
                  ERROR conda.cli.main_run:execute(33): Subprocess for 'conda run ['python', 'TAD_GUI_Contoller.py']' command failed. (See above for error)

                  Other info: When I used opencv-python (Error was similar like above except it had - Could not load the Qt platform plugin "xcb" in ".../python3.7/site-packages/cv2/qt/plugins" even though it was found.). I am using docker (with Ubuntu 18 + WSL2). The problem persist only in docker container. (The python codes work fine in windows)

                  Am I missing some Ubuntu libraries? I tried installing libxcb's and many other libraries. It just does not work. Or is it related to PyQt5?

                  Pablo J. RoginaP Offline
                  Pablo J. RoginaP Offline
                  Pablo J. Rogina
                  wrote on last edited by Pablo J. Rogina
                  #16

                  @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                  qt.qpa.xcb: could not connect to display

                  Are you sure you have an X server running and available?

                  I am using docker (with Ubuntu 18 + WSL2). The problem persist only in docker container.

                  Please be aware that you have a (very) unusual environment.

                  Given that Docker is involved you may need to check how to make the container output work properly under X...

                  Upvote the answer(s) that helped you solve the issue
                  Use "Topic Tools" button to mark your post as Solved
                  Add screenshots via postimage.org
                  Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

                  Y 1 Reply Last reply
                  0
                  • Pablo J. RoginaP Pablo J. Rogina

                    @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                    qt.qpa.xcb: could not connect to display

                    Are you sure you have an X server running and available?

                    I am using docker (with Ubuntu 18 + WSL2). The problem persist only in docker container.

                    Please be aware that you have a (very) unusual environment.

                    Given that Docker is involved you may need to check how to make the container output work properly under X...

                    Y Offline
                    Y Offline
                    yashwant
                    wrote on last edited by
                    #17

                    @Pablo-J-Rogina said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                    rly under

                    1. It is just standard docker windows setup (It just uses the WSL2). It is the standard installation process.
                    2. How can I check if the Xserver is running?

                    Thanks !

                    1 Reply Last reply
                    0
                    • Y Offline
                      Y Offline
                      yashwant
                      wrote on last edited by
                      #18

                      I am just trying to open a python GUI(which opens fine in windows 10) using docker setup. I did install docker for windows using the standard procedure. And I can load the python codes (without .ui - python files without GUI) into the container without any problem. The problem arises only when I try to load python files with GUI.

                      Pablo J. RoginaP 1 Reply Last reply
                      0
                      • Y yashwant

                        I am just trying to open a python GUI(which opens fine in windows 10) using docker setup. I did install docker for windows using the standard procedure. And I can load the python codes (without .ui - python files without GUI) into the container without any problem. The problem arises only when I try to load python files with GUI.

                        Pablo J. RoginaP Offline
                        Pablo J. RoginaP Offline
                        Pablo J. Rogina
                        wrote on last edited by
                        #19

                        @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                        The problem arises only when I try to load python files with GUI.

                        That's the point. You may need to check how to make a Docker container use the GUI of the host...

                        Upvote the answer(s) that helped you solve the issue
                        Use "Topic Tools" button to mark your post as Solved
                        Add screenshots via postimage.org
                        Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

                        Y 1 Reply Last reply
                        0
                        • A Offline
                          A Offline
                          alphaomega
                          wrote on last edited by alphaomega
                          #20

                          Replacing opencv-python with opencv-python-headless is one option. However, for some reasons if you want to keep the library, then you could add following lines after import cv2:

                          import os, sys
                          ci_build_and_not_headless = False
                          try:
                              from cv2.version import ci_build, headless
                              ci_and_not_headless = ci_build and not headless
                          except:
                              pass
                          if sys.platform.startswith("linux") and ci_and_not_headless:
                              os.environ.pop("QT_QPA_PLATFORM_PLUGIN_PATH")
                          if sys.platform.startswith("linux") and ci_and_not_headless:
                              os.environ.pop("QT_QPA_FONTDIR")
                          

                          This is based on the cv2's init file . What it does is essentially removing environment variables that are added by the init file (This are only done at runtime and does not have permanent effect upon your system.)

                          1 Reply Last reply
                          1
                          • Pablo J. RoginaP Pablo J. Rogina

                            @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                            The problem arises only when I try to load python files with GUI.

                            That's the point. You may need to check how to make a Docker container use the GUI of the host...

                            Y Offline
                            Y Offline
                            yashwant
                            wrote on last edited by
                            #21

                            @Pablo-J-Rogina said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                            UI of the host..

                            Yes that was my goal (docker with gui)! and above mentioned was my error when I try GUI on docker.! Anyway thanks!

                            Pablo J. RoginaP 1 Reply Last reply
                            0
                            • Y yashwant

                              @Pablo-J-Rogina said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                              UI of the host..

                              Yes that was my goal (docker with gui)! and above mentioned was my error when I try GUI on docker.! Anyway thanks!

                              Pablo J. RoginaP Offline
                              Pablo J. RoginaP Offline
                              Pablo J. Rogina
                              wrote on last edited by
                              #22

                              @yashwant said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                              that was my goal (docker with gui)!

                              Yes, I understand that. Please take into account that this issue is not related (or produced by) Qt itself so the solution might come from some other source(s), not only this forum

                              Upvote the answer(s) that helped you solve the issue
                              Use "Topic Tools" button to mark your post as Solved
                              Add screenshots via postimage.org
                              Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

                              1 Reply Last reply
                              0
                              • R Offline
                                R Offline
                                redeyed
                                wrote on last edited by redeyed
                                #23

                                @jeremy_k said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                                worka

                                Hello guys, so the problem is that import cv2 sets QT_* env vars.
                                I came to this workaround, maybe it will help someone:

                                    import cv2
                                    for k, v in os.environ.items():
                                        if k.startswith("QT_") and "cv2" in v:
                                            del os.environ[k]
                                
                                A 1 Reply Last reply
                                4
                                • O Offline
                                  O Offline
                                  OBaladi
                                  wrote on last edited by
                                  #24

                                  I solved the problem by downgrading the cv2 version, simply run
                                  python3 -m pip install opencv-contrib-python==4.1.0.25
                                  i used to have the 4.5.3.56

                                  1 Reply Last reply
                                  0
                                  • L lvlanson

                                    Hey there,

                                    I am working on a big project, creating a GUI for working with convolutional neural networks. I need to use cv2 for image processing. For some reason I cannot import cv2 without my application creating an error.

                                    I am using pycharm as an IDE which is handling my virtual environment via pip. The librarys I use are the following:

                                    • PyQt5
                                    • pyqtchart
                                    • pyyaml
                                    • Pillow
                                    • tensorflow
                                    • distro
                                    • numpy
                                    • sklearn
                                    • pandas
                                    • opencv-python

                                    When I use cv2 I get the following error-message:

                                    qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "$HOME/Documents/gui_nn/venv/lib/python3.8/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, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl.

                                    eyllanescE Offline
                                    eyllanescE Offline
                                    eyllanesc
                                    wrote on last edited by
                                    #25

                                    @lvlanson Also see https://stackoverflow.com/a/68417901/6622587

                                    If you want me to help you develop some work then you can write to my email: e.yllanescucho@gmal.com.

                                    1 Reply Last reply
                                    0
                                    • T Offline
                                      T Offline
                                      Thiago Oliveira
                                      wrote on last edited by
                                      #26

                                      @Hikari-Tretaki, muito obrigado por sua ajuda. Também consegui resolver o meu problema com sua dica.

                                      1 Reply Last reply
                                      0
                                      • R redeyed

                                        @jeremy_k said in Using PyQt5 with opencv-python (cv2) causes error "could not load Qt platform plugin xcb even though it was found":

                                        worka

                                        Hello guys, so the problem is that import cv2 sets QT_* env vars.
                                        I came to this workaround, maybe it will help someone:

                                            import cv2
                                            for k, v in os.environ.items():
                                                if k.startswith("QT_") and "cv2" in v:
                                                    del os.environ[k]
                                        
                                        A Offline
                                        A Offline
                                        aria212019005
                                        wrote on last edited by
                                        #27

                                        @redeyed Thankyou, I was confused around installing

                                        opencv-python
                                        

                                        and

                                        opencv-python-headless
                                        

                                        before this. But it ends with "we need both libraries, and this"

                                        1 Reply Last reply
                                        0
                                        • H Hikari Tretaki

                                          @lvlanson I had the same problem. You can install headless opencv without GUI. Then it works.

                                          pip install opencv-python-headless

                                          V Offline
                                          V Offline
                                          Vijay Kumar
                                          wrote on last edited by
                                          #28

                                          @Hikari-Tretaki Thank you so much, installing opencv-python-headless fixed the issue

                                          1 Reply Last reply
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