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

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  • B buhtz
    18 May 2023, 10:50

    Hello,
    I'm not sure what is going on here. So before talking about a solution for the error message it is important to me to understand its background.

    The environment is Debian 11, Python3 and PyQt. I was migrating a PyQt5 application to PyQt6. PyQt6 is installed via PyPi because Debian 11 doesn't offer it.

    Starting the application gives me that error:

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

    This error doesn't appear when using PyQt5. It seems there is an empty search path. I don't know why.

    Via git grep I verified that the string "xcb" doesn't exist in my code.

    I don't know what a "Qt plugin" is. And I don't know what "xcb" stands for.

    I asked synaptics what is installed.

    • libx11-xcb-dev
    • libx11-xcb1
    • libx11-xcb1:386
    • libxcb-imdkit1
    • python3-xcffib

    There are also some "python3-pyqt5*" packages.

    There is no "qt6" package installed or available for Debian 11. Maybe this is the root of the problem?

    To decide what to do with my application I need to deeper understand the cause of the problem. I might have to support Pyqt5 and 6 when it is not available in Debian 11 (no matter that Debian 12 release is near).

    J Offline
    J Offline
    JonB
    wrote on 18 May 2023, 13:28 last edited by JonB
    #2

    @buhtz
    xcb is indeed for X11 screen display. Set environment variable QT_DEBUG_PLUGINS to 1 and then run your application. It will produce diagnostic output from which you/we can gather what it is looking for where and why it didn't get it.

    B 1 Reply Last reply 18 May 2023, 14:35
    2
    • J JonB
      18 May 2023, 13:28

      @buhtz
      xcb is indeed for X11 screen display. Set environment variable QT_DEBUG_PLUGINS to 1 and then run your application. It will produce diagnostic output from which you/we can gather what it is looking for where and why it didn't get it.

      B Offline
      B Offline
      buhtz
      wrote on 18 May 2023, 14:35 last edited by
      #3

      By the way. I installed Qt6 in Debian 11 from its backports repo. Even the qt plugins package is installed now.

      qt.core.plugin.factoryloader: checking directory path "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms" ...
      qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqvkkhrdisplay.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqminimalegl.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqvnc.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqwayland-generic.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqminimal.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqeglfs.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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: looking at "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqwayland-egl.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqoffscreen.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqlinuxfb.so"
      qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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: checking directory path "/usr/bin/platforms" ...
      qt.core.library: "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: Kann die Shared-Object-Datei nicht öffnen: Datei oder Verzeichnis nicht gefunden)
      qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: 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: vkkhrdisplay, minimalegl, vnc, wayland, minimal, eglfs, xcb, wayland-egl, offscreen, linuxfb.
      
      Aborted
      
      JoeCFDJ 1 Reply Last reply 18 May 2023, 15:01
      0
      • B buhtz
        18 May 2023, 14:35

        By the way. I installed Qt6 in Debian 11 from its backports repo. Even the qt plugins package is installed now.

        qt.core.plugin.factoryloader: checking directory path "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms" ...
        qt.core.plugin.factoryloader: looking at "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqvkkhrdisplay.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqminimalegl.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqvnc.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqwayland-generic.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqminimal.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqeglfs.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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: looking at "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqwayland-egl.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqoffscreen.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqlinuxfb.so"
        qt.core.plugin.loader: Found metadata in lib /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/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: checking directory path "/usr/bin/platforms" ...
        qt.core.library: "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so" cannot load: Cannot load library /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: Kann die Shared-Object-Datei nicht öffnen: Datei oder Verzeichnis nicht gefunden)
        qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so" : "Cannot load library /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so: (libxcb-cursor.so.0: 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: vkkhrdisplay, minimalegl, vnc, wayland, minimal, eglfs, xcb, wayland-egl, offscreen, linuxfb.
        
        Aborted
        
        JoeCFDJ Offline
        JoeCFDJ Offline
        JoeCFD
        wrote on 18 May 2023, 15:01 last edited by JoeCFD
        #4

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

        libqxcb.so

        First, /home/user/ is not a good location. I guess you have /opt dir and install the package over there. When you install your package, you may have options for location.
        Second, try:
        ldd /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so
        to see if its all dependencies are available. If one of its dependencies is not installed, it can not be loaded. It is likely that xcb libs are not installed.
        On my computer, the following libs are needed for libqxcb.so

        libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f2f41c45000)
        libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f2f41a40000)
        libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f2f4183b000)
        libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f2f41638000)
        libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f2f41432000)
        libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f2f4122f000)
        libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f2f4101f000)
        libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f2f40e1b000)
        libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f2f40c0e000)
        libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f2f40a0a000)
        libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f2f40803000)
        libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f2f405fb000)
        libxcb-xinerama.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinerama.so.0 (0x00007f2f403f8000)
        libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f2f401dc000)
        libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f2f3ffb4000)
        libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f2f3fda2000)
        libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f2f3fa6a000)
        
        B 2 Replies Last reply 18 May 2023, 15:52
        0
        • JoeCFDJ JoeCFD
          18 May 2023, 15:01

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

          libqxcb.so

          First, /home/user/ is not a good location. I guess you have /opt dir and install the package over there. When you install your package, you may have options for location.
          Second, try:
          ldd /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so
          to see if its all dependencies are available. If one of its dependencies is not installed, it can not be loaded. It is likely that xcb libs are not installed.
          On my computer, the following libs are needed for libqxcb.so

          libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f2f41c45000)
          libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f2f41a40000)
          libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f2f4183b000)
          libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f2f41638000)
          libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f2f41432000)
          libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f2f4122f000)
          libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f2f4101f000)
          libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f2f40e1b000)
          libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f2f40c0e000)
          libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f2f40a0a000)
          libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f2f40803000)
          libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f2f405fb000)
          libxcb-xinerama.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinerama.so.0 (0x00007f2f403f8000)
          libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f2f401dc000)
          libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f2f3ffb4000)
          libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f2f3fda2000)
          libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f2f3fa6a000)
          
          B Offline
          B Offline
          buhtz
          wrote on 18 May 2023, 15:52 last edited by
          #5
          This post is deleted!
          1 Reply Last reply
          0
          • JoeCFDJ JoeCFD
            18 May 2023, 15:01

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

            libqxcb.so

            First, /home/user/ is not a good location. I guess you have /opt dir and install the package over there. When you install your package, you may have options for location.
            Second, try:
            ldd /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so
            to see if its all dependencies are available. If one of its dependencies is not installed, it can not be loaded. It is likely that xcb libs are not installed.
            On my computer, the following libs are needed for libqxcb.so

            libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f2f41c45000)
            libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f2f41a40000)
            libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f2f4183b000)
            libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f2f41638000)
            libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f2f41432000)
            libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f2f4122f000)
            libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f2f4101f000)
            libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f2f40e1b000)
            libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f2f40c0e000)
            libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f2f40a0a000)
            libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f2f40803000)
            libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f2f405fb000)
            libxcb-xinerama.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinerama.so.0 (0x00007f2f403f8000)
            libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f2f401dc000)
            libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f2f3ffb4000)
            libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f2f3fda2000)
            libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f2f3fa6a000)
            
            B Offline
            B Offline
            buhtz
            wrote on 18 May 2023, 16:12 last edited by
            #6

            libqxcb.so

            First, /home/user/ is not a good location. I guess you have /opt dir and install the package over there. When you install your package, you may have options for location.

            I don't have "options for location". PyQt6 was installed from PyPi via python3 -m pip install PyQt6.

            I'm the maintainer of a PyQt using GUI application. And I have to think about how my users deal with things like this. Usually they should be able to install everything via there GNU/Linux distribution repository. But in Debian 11 PyQt6 is not available as a Debian package but only via PyPi. Using PyPi is the "maximum" I can ask my users for. Modifying install locations or building themself is not an option here. ;)

            I still don't understand what that plugin is for and who is responsible. It resists in the PyQt6 install folder. Why? Isn't it related to vanilla Qt and not to its Python binding?

            Second, try:
            ldd /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so

            	linux-vdso.so.1 (0x00007ffd0d7fe000)
            	libQt6XcbQpa.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6XcbQpa.so.6 (0x00007f8a2c277000)
            	libxkbcommon-x11.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007f8a2c23a000)
            	libxkbcommon.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007f8a2c1f7000)
            	libxcb-cursor.so.0 => not found
            	libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f8a2c1f0000)
            	libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f8a2c1ea000)
            	libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f8a2bfe5000)
            	libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f8a2bfd3000)
            	libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f8a2bdcf000)
            	libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f8a2bdca000)
            	libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f8a2bdc0000)
            	libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f8a2bdb6000)
            	libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f8a2bda5000)
            	libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f8a2bda0000)
            	libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f8a2bd82000)
            	libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f8a2bd57000)
            	libQt6OpenGL.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6OpenGL.so.6 (0x00007f8a2bcb5000)
            	libQt6Gui.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007f8a2b2f3000)
            	libGL.so.1 => /usr/lib/x86_64-linux-gnu/libGL.so.1 (0x00007f8a2b26a000)
            	libQt6Core.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007f8a2abe1000)
            	libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f8a2abdc000)
            	libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f8a2aa99000)
            	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8a2aa93000)
            	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8a2aa71000)
            	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8a2a8a2000)
            	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8a2a75e000)
            	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8a2a744000)
            	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8a2a570000)
            	libxcb-cursor.so.0 => not found
            	libglib-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f8a2a441000)
            	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f8a2a43a000)
            	libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f8a2a432000)
            	libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f8a2a42d000)
            	libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f8a2a227000)
            	libEGL.so.1 => /usr/lib/x86_64-linux-gnu/libEGL.so.1 (0x00007f8a2a212000)
            	libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f8a2a1ca000)
            	libQt6DBus.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007f8a2a104000)
            	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8a2a0e7000)
            	libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f8a2a024000)
            	libGLdispatch.so.0 => /usr/lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007f8a29f6c000)
            	libGLX.so.0 => /usr/lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f8a29f38000)
            	libicui18n.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicui18n.so.56 (0x00007f8a29a9d000)
            	libicuuc.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicuuc.so.56 (0x00007f8a296e5000)
            	libicudata.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicudata.so.56 (0x00007f8a27d02000)
            	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8a27cf8000)
            	/lib64/ld-linux-x86-64.so.2 (0x00007f8a2c331000)
            	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f8a27c85000)
            	libbsd.so.0 => /usr/lib/x86_64-linux-gnu/libbsd.so.0 (0x00007f8a27c6c000)
            	libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f8a27c3d000)
            	libuuid.so.1 => /usr/lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f8a27c34000)
            	libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f8a27bdf000)
            	libpng16.so.16 => /usr/lib/x86_64-linux-gnu/libpng16.so.16 (0x00007f8a27ba5000)
            	libbrotlidec.so.1 => /usr/lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007f8a27b95000)
            	libmd.so.0 => /usr/lib/x86_64-linux-gnu/libmd.so.0 (0x00007f8a27b88000)
            	libsystemd.so.0 => /usr/lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007f8a27ad3000)
            	libbrotlicommon.so.1 => /usr/lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007f8a27ab0000)
            	liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f8a27a88000)
            	libzstd.so.1 => /usr/lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f8a279ad000)
            	liblz4.so.1 => /usr/lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f8a27988000)
            	libgcrypt.so.20 => /usr/lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007f8a27868000)
            	libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f8a27842000)
            
            
            JoeCFDJ 1 Reply Last reply 18 May 2023, 16:38
            0
            • B buhtz
              18 May 2023, 16:12

              libqxcb.so

              First, /home/user/ is not a good location. I guess you have /opt dir and install the package over there. When you install your package, you may have options for location.

              I don't have "options for location". PyQt6 was installed from PyPi via python3 -m pip install PyQt6.

              I'm the maintainer of a PyQt using GUI application. And I have to think about how my users deal with things like this. Usually they should be able to install everything via there GNU/Linux distribution repository. But in Debian 11 PyQt6 is not available as a Debian package but only via PyPi. Using PyPi is the "maximum" I can ask my users for. Modifying install locations or building themself is not an option here. ;)

              I still don't understand what that plugin is for and who is responsible. It resists in the PyQt6 install folder. Why? Isn't it related to vanilla Qt and not to its Python binding?

              Second, try:
              ldd /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/libqxcb.so

              	linux-vdso.so.1 (0x00007ffd0d7fe000)
              	libQt6XcbQpa.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6XcbQpa.so.6 (0x00007f8a2c277000)
              	libxkbcommon-x11.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007f8a2c23a000)
              	libxkbcommon.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007f8a2c1f7000)
              	libxcb-cursor.so.0 => not found
              	libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f8a2c1f0000)
              	libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f8a2c1ea000)
              	libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f8a2bfe5000)
              	libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f8a2bfd3000)
              	libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f8a2bdcf000)
              	libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f8a2bdca000)
              	libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f8a2bdc0000)
              	libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f8a2bdb6000)
              	libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f8a2bda5000)
              	libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f8a2bda0000)
              	libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f8a2bd82000)
              	libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f8a2bd57000)
              	libQt6OpenGL.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6OpenGL.so.6 (0x00007f8a2bcb5000)
              	libQt6Gui.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007f8a2b2f3000)
              	libGL.so.1 => /usr/lib/x86_64-linux-gnu/libGL.so.1 (0x00007f8a2b26a000)
              	libQt6Core.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007f8a2abe1000)
              	libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f8a2abdc000)
              	libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f8a2aa99000)
              	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8a2aa93000)
              	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8a2aa71000)
              	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8a2a8a2000)
              	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8a2a75e000)
              	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8a2a744000)
              	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8a2a570000)
              	libxcb-cursor.so.0 => not found
              	libglib-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f8a2a441000)
              	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f8a2a43a000)
              	libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f8a2a432000)
              	libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f8a2a42d000)
              	libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f8a2a227000)
              	libEGL.so.1 => /usr/lib/x86_64-linux-gnu/libEGL.so.1 (0x00007f8a2a212000)
              	libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f8a2a1ca000)
              	libQt6DBus.so.6 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007f8a2a104000)
              	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8a2a0e7000)
              	libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f8a2a024000)
              	libGLdispatch.so.0 => /usr/lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007f8a29f6c000)
              	libGLX.so.0 => /usr/lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f8a29f38000)
              	libicui18n.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicui18n.so.56 (0x00007f8a29a9d000)
              	libicuuc.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicuuc.so.56 (0x00007f8a296e5000)
              	libicudata.so.56 => /home/user/.local/lib/python3.9/site-packages/PyQt6/Qt6/plugins/platforms/../../lib/libicudata.so.56 (0x00007f8a27d02000)
              	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8a27cf8000)
              	/lib64/ld-linux-x86-64.so.2 (0x00007f8a2c331000)
              	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f8a27c85000)
              	libbsd.so.0 => /usr/lib/x86_64-linux-gnu/libbsd.so.0 (0x00007f8a27c6c000)
              	libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f8a27c3d000)
              	libuuid.so.1 => /usr/lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f8a27c34000)
              	libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f8a27bdf000)
              	libpng16.so.16 => /usr/lib/x86_64-linux-gnu/libpng16.so.16 (0x00007f8a27ba5000)
              	libbrotlidec.so.1 => /usr/lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x00007f8a27b95000)
              	libmd.so.0 => /usr/lib/x86_64-linux-gnu/libmd.so.0 (0x00007f8a27b88000)
              	libsystemd.so.0 => /usr/lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007f8a27ad3000)
              	libbrotlicommon.so.1 => /usr/lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x00007f8a27ab0000)
              	liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f8a27a88000)
              	libzstd.so.1 => /usr/lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f8a279ad000)
              	liblz4.so.1 => /usr/lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f8a27988000)
              	libgcrypt.so.20 => /usr/lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007f8a27868000)
              	libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f8a27842000)
              
              
              JoeCFDJ Offline
              JoeCFDJ Offline
              JoeCFD
              wrote on 18 May 2023, 16:38 last edited by JoeCFD
              #7

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

              do not know anything about python. /home/user/.local/ does not look good.

              libxcb-cursor.so.0 => not found

              this one libxcb-cursor.so.0 is not installed.
              sudo apt-get install -y libxcb-cursor-dev or
              sudo apt-get install -y libxcb-cursor is good enough.

              think a plugin is similar to a dynamically linked lib. But your app does not need to be linked to it in building, instead loads it at running time. Sure your app has to know its path. In Qt, its path is set for your app if qt path is known.

              I 1 Reply Last reply 16 Dec 2023, 08:53
              4
              • B Offline
                B Offline
                buhtz
                wrote on 18 May 2023, 19:53 last edited by
                #8

                That solved the problem.
                Thanks a lot for helping me and investing your time.

                - 1 Reply Last reply 6 Sept 2024, 00:29
                0
                • B buhtz has marked this topic as solved on 18 May 2023, 19:53
                • JoeCFDJ JoeCFD
                  18 May 2023, 16:38

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

                  do not know anything about python. /home/user/.local/ does not look good.

                  libxcb-cursor.so.0 => not found

                  this one libxcb-cursor.so.0 is not installed.
                  sudo apt-get install -y libxcb-cursor-dev or
                  sudo apt-get install -y libxcb-cursor is good enough.

                  think a plugin is similar to a dynamically linked lib. But your app does not need to be linked to it in building, instead loads it at running time. Sure your app has to know its path. In Qt, its path is set for your app if qt path is known.

                  I Offline
                  I Offline
                  Ikaros
                  wrote on 16 Dec 2023, 08:53 last edited by
                  #9

                  @JoeCFD thank u so much!

                  1 Reply Last reply
                  0
                  • B buhtz
                    18 May 2023, 19:53

                    That solved the problem.
                    Thanks a lot for helping me and investing your time.

                    - Offline
                    - Offline
                    -Salih123
                    wrote on 6 Sept 2024, 00:29 last edited by
                    #10

                    @buhtz
                    hello buhtz
                    I also had a similar problem
                    I get this error after transferring the codes to my own computer at the end of a project I carried out jointly with my friend.

                    QObject::moveToThread: The current thread (0x25c9e90) is not the object's thread (0x2dfe0e0).
                    Cannot move to target array (0x25c9e90)

                    qt.qpa.plugin: Could not load Qt platform plugin "xcb" in "/usr/local/lib/python3.8/dist-packages/cv2/qt/plugins" even though it is present.
                    This application failed to start because no Qt platform plug-ins could be started. Reinstalling the app 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.

                    Canceled (core dumped)

                    Can you elaborate a little more on how you solved it?

                    Pl45m4P 1 Reply Last reply 6 Sept 2024, 02:08
                    0
                    • - -Salih123
                      6 Sept 2024, 00:29

                      @buhtz
                      hello buhtz
                      I also had a similar problem
                      I get this error after transferring the codes to my own computer at the end of a project I carried out jointly with my friend.

                      QObject::moveToThread: The current thread (0x25c9e90) is not the object's thread (0x2dfe0e0).
                      Cannot move to target array (0x25c9e90)

                      qt.qpa.plugin: Could not load Qt platform plugin "xcb" in "/usr/local/lib/python3.8/dist-packages/cv2/qt/plugins" even though it is present.
                      This application failed to start because no Qt platform plug-ins could be started. Reinstalling the app 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.

                      Canceled (core dumped)

                      Can you elaborate a little more on how you solved it?

                      Pl45m4P Offline
                      Pl45m4P Offline
                      Pl45m4
                      wrote on 6 Sept 2024, 02:08 last edited by
                      #11

                      @Salih123 said in Could not load the Qt platform plugin "xcb" in "" even though it was found.":

                      QObject::moveToThread: The current thread (0x25c9e90) is not the object's thread (0x2dfe0e0).
                      Cannot move to target array (0x25c9e90)

                      This indicates that there's something wrong in your code. You are probably moving some QObjects from/to a thread.

                      Can you elaborate a little more on how you solved it?

                      Have you tried to install what @buhtz posted above?


                      If debugging is the process of removing software bugs, then programming must be the process of putting them in.

                      ~E. W. Dijkstra

                      1 Reply Last reply
                      1
                      • S Offline
                        S Offline
                        saundecp
                        wrote on 26 Nov 2024, 21:20 last edited by
                        #12

                        Leaving a comment here because this was a top result when I had the exact error. In my case, I had pip installed opencv, and that pip-installed version had conflicts with the system qt. Steps that ultimately resolved the problem are here on Stack Overflow.

                        1 Reply Last reply
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