我知道有很多关于这个主题的答案，但是没有一个对我有帮助。我使用Oracle VM Virtual Box上的Ubuntu 20.04，并且遇到了和其他人完全相同的错误。 按照官方Qt手册构建Qt6源代码后，我尝试运行不同的项目以测试一切是否正常。控制台类型的项目构建和运行正常，没有错误。不幸的是，当我尝试运行窗口小部件类型的应用程序时，它会出现众所周知的错误。
t.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, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.
libqxcb.so文件，于是与我分享了这个文件。不幸的是，它并没有帮助太多。只是错误消息有点变化：它说找到了插件，但无法使用。我尝试了网络上的不同解决方案，但没有一个有效。其中最流行的一个是...sudo apt install libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-render-util0
没有影响。
此外，使用环境变量QT_DEBUG_PLUGINS=1可以获得更详细的输出：
QFactoryLoader::QFactoryLoader() checking directory path "/home/curiouspan/qt6-build/qtbase/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqeglfs.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqeglfs.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"eglfs"
]
},
"archreq": 1,
"className": "QEglFSIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqlinuxfb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"linuxfb"
]
},
"archreq": 1,
"className": "QLinuxFbIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqminimal.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqminimal.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archreq": 1,
"className": "QMinimalIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("minimal")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqminimalegl.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqminimalegl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimalegl"
]
},
"archreq": 1,
"className": "QMinimalEglIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqoffscreen.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqoffscreen.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archreq": 1,
"className": "QOffscreenIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqvnc.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqvnc.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"vnc"
]
},
"archreq": 1,
"className": "QVncIntegrationPlugin",
"debug": true,
"version": 393728
}
Got keys from plugin meta data QList("vnc")
QFactoryLoader::QFactoryLoader() looking at "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so"
Found metadata in lib /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"archreq": 0,
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 393728
}
Got keys from plugin meta data QList("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/curiouspan/QtTestProjects/build-WidgetTestApp-Own_Desktop-Debug/platforms" ...
Cannot load library /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so: (libQt6XcbQpa.so.6: cannot open shared object file: No such file or directory)
QLibraryPrivate::loadPlugin failed on "/home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so" : "Cannot load library /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so: (libQt6XcbQpa.so.6: cannot open shared object file: No such file or directory)"
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, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.
这表明缺少libQt6XcbQpa.so.6文件。
运行ldd /home/curiouspan/qt6-build/qtbase/plugins/platforms/libqxcb.so以显示依赖项，我得到了以下输出：
linux-vdso.so.1 (0x00007fffc8770000)
libQt6XcbQpa.so.6 => not found
libQt6Gui.so.6 => /home/curiouspan/qt6-build/qtbase/plugins/platforms/../../lib/libQt6Gui.so.6 (0x00007f0873306000)
libQt6Core.so.6 => /home/curiouspan/qt6-build/qtbase/plugins/platforms/../../lib/libQt6Core.so.6 (0x00007f087295d000)
libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f087277c000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f087258a000)
libEGL.so.1 => /lib/x86_64-linux-gnu/libEGL.so.1 (0x00007f0872573000)
libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6 (0x00007f0872436000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f0872430000)
libQt6DBus.so.6 => /home/curiouspan/qt6-build/qtbase/plugins/platforms/../../lib/libQt6DBus.so.6 (0x00007f0872262000)
libGLX.so.0 => /lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f087222e000)
libOpenGL.so.0 => /lib/x86_64-linux-gnu/libOpenGL.so.0 (0x00007f0872202000)
所以这个文件确实丢失了。 可能的问题是什么，我该如何解决？谢谢！
~/qt6）的步骤。 - Botjelibxkbcommon-dev软件包？ - Ross Rogers