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

[Phsnomy]

I'm quite sure it's a qt issue. I got this message when I run flatpak apps and wireshark.
With QT_DEBUG_PLUGINS set to 1, I got following msgs:

sudo QT_DEBUG_PLUGINS=1 wireshark                                                                                                                                                       
QFactoryLoader::QFactoryLoader() checking directory path "/usr/lib64/qt5/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/KWinQpaPlugin.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/KWinQpaPlugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-org.kde.kwin.qpa"
        ]
    },
    "archreq": 0,
    "className": "KWinIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("wayland-org.kde.kwin.qpa")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqeglfs.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "archreq": 0,
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqlinuxfb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "linuxfb"
        ]
    },
    "archreq": 0,
    "className": "QLinuxFbIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqminimal.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "archreq": 0,
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqminimalegl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "archreq": 0,
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqoffscreen.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "archreq": 0,
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqvnc.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "archreq": 0,
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-egl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-egl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-egl"
        ]
    },
    "archreq": 0,
    "className": "QWaylandEglPlatformIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("wayland-egl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-generic.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-generic.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland"
        ]
    },
    "archreq": 0,
    "className": "QWaylandIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("wayland")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-egl.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-egl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-xcomposite-egl"
        ]
    },
    "archreq": 0,
    "className": "QWaylandXCompositeEglPlatformIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("wayland-xcomposite-egl")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-glx.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqwayland-xcomposite-glx.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "wayland-xcomposite-glx"
        ]
    },
    "archreq": 0,
    "className": "QWaylandXCompositeGlxPlatformIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("wayland-xcomposite-glx")
QFactoryLoader::QFactoryLoader() looking at "/usr/lib64/qt5/plugins/platforms/libqxcb.so"
Found metadata in lib /usr/lib64/qt5/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archreq": 0,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 330752
}


Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/bin/platforms" ...
loaded library "/usr/lib64/qt5/plugins/platforms/libqxcb.so"
qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
loaded library "/usr/lib64/qt5/plugins/platforms/libqwayland-generic.so"
error: XDG_RUNTIME_DIR not set in the environment.
Failed to create wl_display (No such file or directory)
qt.qpa.plugin: Could not load the Qt platform plugin "wayland" 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: wayland-org.kde.kwin.qpa, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

[1]    14744 abort      sudo QT_DEBUG_PLUGINS=1 wireshark

How can I fix this?

[JonB]

@Phsnomy said in qt.qpa.xcb: could not connect to display:

error: XDG_RUNTIME_DIR not set in the environment.

I'm not an expert in this area, but this is telling you you need to set that environment variable to make your situation work. I suggest you Google for wayland xdg_runtime_dir and read what others say about this.

[mrjj]

Hi and welcome to the forums

What is the Os ?

Did you try
export DISPLAY=:0.0
wireshark
from shell ?