RaspberryPi Qt 5.15.2: qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" * failed to add service - already in use?

CaptainHatteras · wrote on 9 Dec 2021, 20:33

I know there are many similar questions, but all the solutions I tried did not work. I could find nothing wrong with the ldd command:

ldd /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/platforms/libqxcb.so
   linux-vdso.so.1 (0xbeee6000)
   /usr/lib/arm-linux-gnueabihf/libarmmem-${PLATFORM}.so => /usr/lib/arm-linux-gnueabihf/libarmmem-v7l.so (0xb6f67000)
   libQt5XcbQpa.so.5 => /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/platforms/../../lib/libQt5XcbQpa.so.5 (0xb6e4c000)
   libfontconfig.so.1 => /usr/lib/arm-linux-gnueabihf/libfontconfig.so.1 (0xb6de7000)
   libfreetype.so.6 => /usr/lib/arm-linux-gnueabihf/libfreetype.so.6 (0xb6d44000)
   libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0xb6d19000)
   libQt5Gui.so.5 => /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/platforms/../../lib/libQt5Gui.so.5 (0xb6761000)
   libQt5DBus.so.5 => /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/platforms/../../lib/libQt5DBus.so.5 (0xb66cb000)
   libQt5Core.so.5 => /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/platforms/../../lib/libQt5Core.so.5 (0xb615e000)
   libGLESv2.so.2 => /usr/lib/arm-linux-gnueabihf/libGLESv2.so.2 (0xb613f000)
   libEGL.so.1 => /usr/lib/arm-linux-gnueabihf/libEGL.so.1 (0xb6120000)
   libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xb60f6000)
   libX11-xcb.so.1 => /usr/lib/arm-linux-gnueabihf/libX11-xcb.so.1 (0xb60e4000)
   libxcb-icccm.so.4 => /usr/lib/arm-linux-gnueabihf/libxcb-icccm.so.4 (0xb60d0000)
   libxcb-image.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-image.so.0 (0xb60bc000)
   libxcb-shm.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-shm.so.0 (0xb60a9000)
   libxcb-util.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-util.so.0 (0xb6094000)
   libxcb-keysyms.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb-keysyms.so.1 (0xb6081000)
   libxcb-randr.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-randr.so.0 (0xb6064000)
   libxcb-render-util.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-render-util.so.0 (0xb6050000)
   libxcb-render.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-render.so.0 (0xb6035000)
   libxcb-shape.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-shape.so.0 (0xb6022000)
   libxcb-sync.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb-sync.so.1 (0xb600c000)
   libxcb-xfixes.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-xfixes.so.0 (0xb5ff5000)
   libxcb-xinerama.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-xinerama.so.0 (0xb5fe2000)
   libxcb-xkb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb-xkb.so.1 (0xb5fbd000)
   libxcb-xinput.so.0 => /usr/lib/arm-linux-gnueabihf/libxcb-xinput.so.0 (0xb5f93000)
   libxcb.so.1 => /usr/lib/arm-linux-gnueabihf/libxcb.so.1 (0xb5f64000)
   libXext.so.6 => /usr/lib/arm-linux-gnueabihf/libXext.so.6 (0xb5f45000)
   libX11.so.6 => /usr/lib/arm-linux-gnueabihf/libX11.so.6 (0xb5e23000)
   libSM.so.6 => /usr/lib/arm-linux-gnueabihf/libSM.so.6 (0xb5e0c000)
   libICE.so.6 => /usr/lib/arm-linux-gnueabihf/libICE.so.6 (0xb5de6000)
   libxkbcommon-x11.so.0 => /usr/lib/arm-linux-gnueabihf/libxkbcommon-x11.so.0 (0xb5dcf000)
   libxkbcommon.so.0 => /usr/lib/arm-linux-gnueabihf/libxkbcommon.so.0 (0xb5d86000)
   libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xb5d73000)
   libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xb5c2c000)
   libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xb5baa000)
   libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb5b7d000)
   libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb5a2f000)
   libgthread-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libgthread-2.0.so.0 (0xb5a1d000)
   libglib-2.0.so.0 => /usr/lib/arm-linux-gnueabihf/libglib-2.0.so.0 (0xb590d000)
   libexpat.so.1 => /lib/arm-linux-gnueabihf/libexpat.so.1 (0xb58cc000)
   libuuid.so.1 => /lib/arm-linux-gnueabihf/libuuid.so.1 (0xb58b5000)
   /lib/ld-linux-armhf.so.3 (0xb6f8f000)
   libpng16.so.16 => /usr/lib/arm-linux-gnueabihf/libpng16.so.16 (0xb5879000)
   libdbus-1.so.3 => /lib/arm-linux-gnueabihf/libdbus-1.so.3 (0xb5828000)
   libicui18n.so.63 => /usr/lib/arm-linux-gnueabihf/libicui18n.so.63 (0xb55da000)
   libicuuc.so.63 => /usr/lib/arm-linux-gnueabihf/libicuuc.so.63 (0xb5454000)
   libicudata.so.63 => /usr/lib/arm-linux-gnueabihf/libicudata.so.63 (0xb3a56000)
   libGLdispatch.so.0 => /usr/lib/arm-linux-gnueabihf/libGLdispatch.so.0 (0xb39d7000)
   libXau.so.6 => /usr/lib/arm-linux-gnueabihf/libXau.so.6 (0xb39c4000)
   libXdmcp.so.6 => /usr/lib/arm-linux-gnueabihf/libXdmcp.so.6 (0xb39af000)
   libbsd.so.0 => /usr/lib/arm-linux-gnueabihf/libbsd.so.0 (0xb3987000)
   libpcre.so.3 => /lib/arm-linux-gnueabihf/libpcre.so.3 (0xb3910000)
   libsystemd.so.0 => /lib/arm-linux-gnueabihf/libsystemd.so.0 (0xb3873000)
   librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xb385c000)
   liblzma.so.5 => /lib/arm-linux-gnueabihf/liblzma.so.5 (0xb382b000)
   liblz4.so.1 => /usr/lib/arm-linux-gnueabihf/liblz4.so.1 (0xb37ff000)
   libgcrypt.so.20 => /lib/arm-linux-gnueabihf/libgcrypt.so.20 (0xb3725000)
   libgpg-error.so.0 => /lib/arm-linux-gnueabihf/libgpg-error.so.0 (0xb36fb000)

The output of the ls command is the following:

ls -l /home/pi/qt-raspberrypi-configuration/build/qtbase/plugins/
total 36
drwxr-xr-x 2 pi pi 4096 Jul 10 18:52 bearer
drwxr-xr-x 2 pi pi 4096 Jul 10 18:55 egldeviceintegrations
drwxr-xr-x 2 pi pi 4096 Jul 10 18:53 generic
drwxr-xr-x 2 pi pi 4096 Jul 10 18:52 imageformats
drwxr-xr-x 2 pi pi 4096 Jul 10 18:50 platforminputcontexts
drwxr-xr-x 2 pi pi 4096 Jul 10 18:55 platforms
drwxr-xr-x 2 pi pi 4096 Jul 10 18:50 platformthemes
drwxr-xr-x 2 pi pi 4096 Jul 10 18:51 sqldrivers
drwxr-xr-x 2 pi pi 4096 Jul 10 18:55 xcbglintegrations

I have tried setting QT_DEBUG_PLUGINS to 1, but I got no additional information.
I downloaded and set up Qt 5.15.2 here. Please note that I have downloaded all the X11 suport.

If it helps, my qt-everywhere-src-5.15.2 folder is in /home/pi and so is my qt-raspberrypi-configuration. My QtCreator version is Qt Creator 4.8.2
Based on Qt 5.11.3 (GCC 8.3.0, 32 bit).

Does anyone know how to fix this? Anyone need more information?

SGaist · 9 Dec 2021, 20:43

Hi and welcome to devnet,

Did you call make install after building Qt ?

CaptainHatteras · S SGaist 9 Dec 2021, 20:37

@SGaist Yes. Sorry for the wait. I can only make a post every ten minutes since I am new.

SGaist · 9 Dec 2021, 20:53

What did you got related to xcb in your plugins debug messages ?

CaptainHatteras · S SGaist 9 Dec 2021, 20:49

@SGaist My exact error message with and without QT_DEBUG_PLUGINS set was the following:

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" * failed to add service - already in use?

at runtime.

SGaist · 9 Dec 2021, 21:06

@CaptainHatteras said in RaspberryPi Qt 5.15.2: qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" * failed to add service - already in use?:

QT_DEBUG_PLUGINS

With it, you should have a truck load of messages on your console with regard to all the plugins being loaded. If not, there there's something off.

CaptainHatteras · 10 Dec 2021, 05:57

@SGaist In my .pro file, I put the following exactly:

QT_DEBUG_PLUGINS = 1

Is this incorrect? Sorry I am very inexperienced :)

jsulm · 10 Dec 2021, 20:43

@CaptainHatteras said in RaspberryPi Qt 5.15.2: qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" * failed to add service - already in use?:

Is this incorrect?

No, its wrong.
You need to put it in terminal where you start your app before you start it.
If you start your app in QtCreator then add it in "Projects/Run/Run Environment".

CaptainHatteras · 10 Dec 2021, 21:00

@jsulm Hi, sorry for the wait. Thank you for the correction. Here is the last part of the QT_DEBUG_PLUGINS output:

QFactoryLoader::QFactoryLoader() checking directory path "/home/pi/dev/cpp_projects/build-QtMotoFitAppBG-Desktop-Debug/egldeviceintegrations" ...
loaded library "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so"
* failed to add service - already in use?
QLibraryPrivate::unload succeeded on "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so" 
QLibraryPrivate::unload succeeded on "/opt/Qt/5.15.2/plugins/platforms/libqeglfs.so"

Here is the full message:

QFactoryLoader::QFactoryLoader() checking directory path "/opt/Qt/5.15.2/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqeglfs.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "archreq": 0,
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqlinuxfb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "linuxfb"
        ]
    },
    "archreq": 0,
    "className": "QLinuxFbIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqminimal.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "archreq": 0,
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqminimalegl.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "archreq": 0,
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqoffscreen.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "archreq": 0,
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqvnc.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "archreq": 0,
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platforms/libqwebgl.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platforms/libqwebgl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "webgl"
        ]
    },
    "archreq": 0,
    "className": "QWebGLIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("webgl")
QFactoryLoader::QFactoryLoader() checking directory path "/home/pi/dev/cpp_projects/build-QtMotoFitAppBG-Desktop-Debug/platforms" ...
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
loaded library "/opt/Qt/5.15.2/plugins/platforms/libqeglfs.so"
QFactoryLoader::QFactoryLoader() checking directory path "/opt/Qt/5.15.2/plugins/platformthemes" ...
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/platformthemes/libqxdgdesktopportal.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/platformthemes/libqxdgdesktopportal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformThemeFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "xdgdesktopportal",
            "flatpak",
            "snap"
        ]
    },
    "archreq": 0,
    "className": "QXdgDesktopPortalThemePlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("xdgdesktopportal", "flatpak", "snap")
QFactoryLoader::QFactoryLoader() checking directory path "/home/pi/dev/cpp_projects/build-QtMotoFitAppBG-Desktop-Debug/platformthemes" ...
QFactoryLoader::QFactoryLoader() checking directory path "/opt/Qt/5.15.2/plugins/egldeviceintegrations" ...
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so, metadata=
{
    "IID": "org.qt-project.qt.qpa.egl.QEglFSDeviceIntegrationFactoryInterface.5.5",
    "MetaData": {
        "Keys": [
            "eglfs_brcm"
        ]
    },
    "archreq": 0,
    "className": "QEglFSBrcmIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("eglfs_brcm")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-emu-integration.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-emu-integration.so, metadata=
{
    "IID": "org.qt-project.qt.qpa.egl.QEglFSDeviceIntegrationFactoryInterface.5.5",
    "MetaData": {
        "Keys": [
            "eglfs_emu"
        ]
    },
    "archreq": 0,
    "className": "QEglFSEmulatorIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("eglfs_emu")
QFactoryLoader::QFactoryLoader() looking at "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-kms-integration.so"
Found metadata in lib /opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-kms-integration.so, metadata=
{
    "IID": "org.qt-project.qt.qpa.egl.QEglFSDeviceIntegrationFactoryInterface.5.5",
    "MetaData": {
        "Keys": [
            "eglfs_kms"
        ]
    },
    "archreq": 0,
    "className": "QEglFSKmsGbmIntegrationPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("eglfs_kms")
QFactoryLoader::QFactoryLoader() checking directory path "/home/pi/dev/cpp_projects/build-QtMotoFitAppBG-Desktop-Debug/egldeviceintegrations" ...
loaded library "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so"
* failed to add service - already in use?
QLibraryPrivate::unload succeeded on "/opt/Qt/5.15.2/plugins/egldeviceintegrations/libqeglfs-brcm-integration.so" 
QLibraryPrivate::unload succeeded on "/opt/Qt/5.15.2/plugins/platforms/libqeglfs.so"

JonB · 12 Oct 2021, 21:00

@CaptainHatteras
I'm afraid it means nothing to me, but Googling libqeglfs failed to add service already in use do these help: