libQt5XcbQpa.so.5: undefined symbol: _ZTI20QEventDispatcherGlib

WindyAwaki

Hello,
I'm trying to run a VPN application "Trojan-Qt5-Linux.AppImage"
The output is as follows:

awaki@ubuntu:~$ export QT_DEBUG_PLUGINS=1
awaki@ubuntu:~$ ./Trojan-Qt5-Linux.AppImage 
QFactoryLoader::QFactoryLoader() checking directory path "/tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/libqxcb.so"
Found metadata in lib /tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archreq": 0,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 331008
}


Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/tmp/.mount_TrojanAJ1rp3/usr/bin/platforms" ...
Cannot load library /tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/libqxcb.so: (/tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/../../lib/libQt5XcbQpa.so.5: undefined symbol: _ZTI20QEventDispatcherGlib, version Qt_5_PRIVATE_API)
QLibraryPrivate::loadPlugin failed on "/tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/libqxcb.so" : "Cannot load library /tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/libqxcb.so: (/tmp/.mount_TrojanAJ1rp3/usr/plugins/platforms/../../lib/libQt5XcbQpa.so.5: undefined symbol: _ZTI20QEventDispatcherGlib, version Qt_5_PRIVATE_API)"
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: xcb.

Aborted (core dumped)

And my path is as follows:

awaki@ubuntu:~$ echo $LD_LIBRARY_PATH
/opt/qt-5.15.2/lib:
awaki@ubuntu:~$ echo $QT_PLUGIN_PATH

awaki@ubuntu:~$

It seems that QT_PLUGIN_PATH is empty

Befor I try this, I have built QT 5.1.2 from source code "qt-everywhere-src-5.15.2.tar.xz" and installed qt-creator from "qt-creator-opensource-linux-x86_64-7.0.0.run". And the Kits of QT-Creator works without any problem.

Hopefully someone can give me some pointers as to solving this.