Hi! Seems you sent this email as an HTML one and probaby not to the bug tracker, so it only made it to the mailing list.
El miércoles, 13 de septiembre de 2023 20:33:59 -03 i...@tutamail.com escribió: > Package: libqt6widgets6 > Version: 6.4.2+dfsg-10 > > Dear developers, > > > I write you because of an issue around the xcb QPA platform plugin. > > Looking at https://doc.qt.io/qt-5/linux-requirements.html and > https://doc.qt.io/qt-6.4/linux-requirements.html for Qt5 and Qt6 > respectively, > I would understand that since xcb QPA "provides the basic functionality > needed by Qt GUI and Qt Widgets to run against X11", all its library > dependencies should be direct or indirect dependencies of the libraries > libqt5gui5 and libqt5widgets5 for Qt5 and qt6-qpa-plugins, libqt6gui6 and > libqt6widgets6 for Qt6 respectively. > > However, I had in Debian 12 (and before also in Debian 10) those Qt6 and Qt5 > libraries installed, while some of the xcb library dependencies were not > installed in my system. > > That was the source of an issue with some software app developed with Qt, > which > I could install on my system, but later it did not work (I'll spare you the > details for now, unless you ask me for them), since I did not have installed > some of those packages like libxcb-cursor0 (Debian 12 issue) or libxcb-util1 > (Debian 10 issue, although in that case I had installed libxcb-util0, which > was > the stable release, while I needed libxcb-util1, which was testing). And this > issue seems to be much more general, as there is this long discussion related > to it: > https://forum.qt.io/topic/93247/qt-qpa-plugin-could-not-load-the-qt-platform-plugin-xcb-in-even-though-it-was-found No, this is another issue. Let me explain by starting how the support is there. I will exemplify it with Qt 5, the logic should also apply to Qt 6. First of all the package shipping X11 support is libqt5gui5: ``` $ dpkg -L libqt5gui5 | grep -i xcb /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.15.10 /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so /usr/lib/x86_64-linux-gnu/qt5/plugins/xcbglintegrations /usr/lib/x86_64-linux-gnu/qt5/plugins/xcbglintegrations/libqxcb-egl-integration.so /usr/lib/x86_64-linux-gnu/qt5/plugins/xcbglintegrations/libqxcb-glx-integration.so /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.15 ``` The libQt5Gui5.so.5.x.y library loads the libqxcb.so plugin listed above when it needs to do X11 rendering. In turn this plugin depends upon: ``` $ objdump -x /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so | grep NEEDED NEEDED libQt5XcbQpa.so.5 NEEDED libQt5Gui.so.5 NEEDED libQt5Core.so.5 NEEDED libstdc++.so.6 NEEDED libc.so.6 ``` And in turn libQt5XcbQpa.so.5: ``` $ objdump -x /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.15 | grep NEEDED NEEDED libfontconfig.so.1 NEEDED libfreetype.so.6 NEEDED libQt5Gui.so.5 NEEDED libQt5DBus.so.5 NEEDED libQt5Core.so.5 NEEDED libX11-xcb.so.1 NEEDED libxcb-icccm.so.4 NEEDED libxcb-image.so.0 NEEDED libxcb-shm.so.0 NEEDED libxcb-keysyms.so.1 NEEDED libxcb-randr.so.0 NEEDED libxcb-render-util.so.0 NEEDED libxcb-render.so.0 NEEDED libxcb-shape.so.0 NEEDED libxcb-sync.so.1 NEEDED libxcb-xfixes.so.0 NEEDED libxcb-xinerama.so.0 NEEDED libxcb-xkb.so.1 NEEDED libxcb-xinput.so.0 NEEDED libxcb.so.1 NEEDED libXrender.so.1 NEEDED libX11.so.6 NEEDED libSM.so.6 NEEDED libICE.so.6 NEEDED libxkbcommon-x11.so.0 NEEDED libxkbcommon.so.0 NEEDED libglib-2.0.so.0 NEEDED libstdc++.so.6 NEEDED libgcc_s.so.1 NEEDED libc.so.6 ``` These are all the libraries required by the plugin + private library. If something else is missing is due to any of those dependencies not bringing in others. But no, that's not your problem. Let's go back to the URL you sent: https://forum.qt.io/topic/93247/qt-qpa-plugin-could-not-load-the-qt-platform-plugin-xcb-in-even-though-it-was-found In there you can read: ``` qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found. ``` Note the "even though it was found" last part. That normally means a broken installation, like having mixed Qt versions in paths (like, one from the Qt installer and one from the system), but could also be do to lack of proper support (headless PC and/or no running X, for example). If this where a bug believe me that Qt would not be part of any Debian stable release :-D Please double check your systems, but be sure that is is 99.9% your issue rather than a Debian-induced one. regards, Lisandro.
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