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

[MarkLTZ]

Hello there!

I have the issue in the object using bundled qt 6.4.0:

# java -cp lib/*:. it.sample.wizard.Main

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wayland-egl")
qt.core.plugin.factoryloader: checking directory path "/usr/lib/jvm/java-11-openjdk-11.0.16.1.1-1.fc36.x86_64/bin/platforms" ...
qt.core.library: "/tmp/QtJambi6.4.0_s0n1k_567645/plugins/platforms/libqwayland-generic.so" cannot load: Cannot load library /tmp/QtJambi6.4.0_s0n1k_567645/plugins/platforms/libqwayland-generic.so: (libQt6WaylandClient.so.6: cannot open shared object file: No such file or directory)
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/tmp/QtJambi6.4.0_s0n1k_567645/plugins/platforms/libqwayland-generic.so" : "Cannot load library /tmp/QtJambi6.4.0_s0n1k_567645/plugins/platforms/libqwayland-generic.so: (libQt6WaylandClient.so.6: cannot open shared object file: No such file or directory)"
qt.qpa.plugin: Could not load the Qt platform plugin "wayland" in "" even though it was found.
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

This is a list of deployed jar files:

# ls -la lib/qt*
-rw-r--r--. 1 s0n1k s0n1k  3781466 Sep 30 17:13 lib/qtjambi-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k 24388645 Sep 30 17:14 lib/qtjambi-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k  2979513 Sep 30 17:13 lib/qt-lib-core-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k   343998 Sep 30 17:13 lib/qt-lib-dbus-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k  5130928 Sep 30 17:13 lib/qt-lib-gui-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k   201365 Sep 30 17:13 lib/qt-lib-svg-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k   507131 Sep 30 17:14 lib/qt-lib-waylandclient-native-linux-x64-6.4.0.jar
-rw-r--r--. 1 s0n1k s0n1k  3557872 Sep 30 17:13 lib/qt-lib-widgets-native-linux-x64-6.4.0.jar

Looking inside QT bundled jar files I found:

# jar tvf lib/qt-lib-waylandclient-native-linux-x64-6.4.0.jar | grep libQt6WaylandClient.so
1276488 Fri Sep 30 17:08:56 CEST 2022 lib/libQt6WaylandClient.so.6.4.0

But it seams it's not auto deployed under /tmp/QtJambi6.4.0_s0n1k_567645:

# ldd /tmp/QtJambi6.4.0_s0n1k_567645/plugins/platforms/libqwayland-generic.so | grep "not found"
	libQt6WaylandClient.so.6 => not found

# ls -la /tmp/QtJambi6.4.0_s0n1k_567645/lib/libQt6WaylandClient*
ls: cannot access '/tmp/QtJambi6.4.0_s0n1k_567645/lib/libQt6WaylandClient*': No such file or directory

Could you please help me?

Thanks,
Marco

[omix]

Oh, that's something missing in QtJambi. thanks for reporting.
Fix it by adding the following line at the beginning of main():

io.qt.QtUtilities.loadQtLibrary("WaylandClient", io.qt.QtUtilities.LibraryRequirementMode.ProvideOnly, "linux");

[MarkLTZ]

it works, but now I have this error:

qt.core.plugin.factoryloader: Got keys from plugin meta data QList()
qt.core.plugin.factoryloader: checking directory path "/usr/lib/jvm/java-11-openjdk-11.0.16.1.1-1.fc36.x86_64/bin/wayland-graphics-integration-client" ...
qt.core.library: "/tmp/QtJambi6.4.0_s0n1k_592474/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so" cannot load: Cannot load library /tmp/QtJambi6.4.0_s0n1k_592474/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so: (libQt6WaylandEglClientHwIntegration.so.6: cannot open shared object file: No such file or directory)
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/tmp/QtJambi6.4.0_s0n1k_592474/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so" : "Cannot load library /tmp/QtJambi6.4.0_s0n1k_592474/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so: (libQt6WaylandEglClientHwIntegration.so.6: cannot open shared object file: No such file or directory)"
qt.qpa.wayland: Failed to load client buffer integration: "wayland-egl"
qt.qpa.wayland: Available client buffer integrations: QList("wayland-egl")

[omix]

Isn't there Qt6WaylandEglClientHwIntegration in the bundle?

Otherwise add:

io.qt.QtUtilities.loadQtLibrary("WaylandEglClientHwIntegration", io.qt.QtUtilities.LibraryRequirementMode.ProvideOnly, "linux");

[omix]

Oh, as I see, you are using QtJambi for Qt 6.4.0. Did you build it yourself from latest release?

[MarkLTZ]

Oh, as I see, you are using QtJambi for Qt 6.4.0. Did you build it yourself from latest release?

Yes I did.

[MarkLTZ]

Still one issue looking for libQt6OpenGL.so.6:

qt.core.plugin.factoryloader: Got keys from plugin meta data QList()
qt.core.plugin.factoryloader: checking directory path "/usr/lib/jvm/java-11-openjdk-11.0.16.1.1-1.fc36.x86_64/bin/wayland-graphics-integration-client" ...
qt.core.library: "/tmp/QtJambi6.4.0_s0n1k_593796/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so" cannot load: Cannot load library /tmp/QtJambi6.4.0_s0n1k_593796/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so: (libQt6OpenGL.so.6: cannot open shared object file: No such file or directory)
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/tmp/QtJambi6.4.0_s0n1k_593796/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so" : "Cannot load library /tmp/QtJambi6.4.0_s0n1k_593796/plugins/wayland-graphics-integration-client/libqt-plugin-wayland-egl.so: (libQt6OpenGL.so.6: cannot open shared object file: No such file or directory)"
qt.qpa.wayland: Failed to load client buffer integration: "wayland-egl"
qt.qpa.wayland: Available client buffer integrations: QList("wayland-egl")

[omix]

Ok, the solution for this kind of error should now be streight forward.
I will take this thread to improve the deployment dependencies. So if you have firther missing things, post it.

[MarkLTZ]

Ok, the solution for this kind of error should now be streight forward. I will take this thread to improve the deployment dependencies. So if you have firther missing things, post it.

I used this as workaround:

io.qt.QtUtilities.loadQtLibrary("OpenGL", io.qt.QtUtilities.LibraryRequirementMode.ProvideOnly, "linux");

Now, no more errors occurs and my app start properly.

I hope a fix will be available soon so I can remove these workarounds.

Thanks for you fast and excellent support.

Marco