@emfo said in X11 Nvidia black window: Skip to content 7 qtws26_logo The Qt Event of the Year: Qt World Summit 2026 Save Your Spot > Brand Logo Home Qt Development General and Desktop X11 Nvidia black window Unsolved General and Desktop 6 Posts 3 Posters 331 Views 3 Watching E Offline emfo wrote 26 days ago last edited by #1 We get a black window when running smallest possible Qt application using OpenGL on Linux with an Nvidia graphics card (proprietary 580.159.03). To rule out environment and driver problems, we have written three corresponding applications using xlib only, xcb only, and a xlib xcb mix. All three of them work on the same Nvidia graphics card in the same environment. The attached xlib.cpp, xcb.cpp, xcb_xlib.cpp and qt.cpp can be built following the instructions in build_and_run.sh (replace the QT path in the script to where your Qt installation is first). Replacing EGL_PLATFORM_XCB_KHR with EGL_PLATFORM_X11_KHR in xcb_xlib.cpp, and using xlib display, causes eglCreatePlatformWindowSurfaceEXT to return a nullptr for EGLSurface in xcb_xlib.cpp, exactly what we see in Qt. Is there something we're missing in qt.cpp to make this work or is this a bug in Qt that can be fixed? We started looking into the Qt source code, the call to eglCreatePlatformWindowSurfaceEXT(EGL_PLATFORM_X11_KHR, xlib display, [...]) returns 0. If we modify Qt to call eglCreatePlatformWindowSurfaceEXT(EGL_PLATFORM_XCB_KHR, xcb connection, [...]), we instead get a valid surface that can be queried with eglQuerySurface that report the correct size. The window is still black but having a surface is a good start for anyone looking into this. Attached source files 16 days later Axel Spoerl Offline Axel Spoerl Moderators wrote 10 days ago last edited by #2 I am using X11 on Nvidia and I don't have this issue. Please post a minimal reproducer here. Software Engineer The Qt Company, Oslo SGaist Offline SGaist Lifetime Qt Champion wrote 10 days ago last edited by #3 Hi and welcome to devnet, You should also provide the kernel version you are using as well graphics card model. Interested in AI ? www.idiap.ch Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct 9 days later E Offline emfo wrote a day ago last edited by #4 @Axel-Spoerl the attached sources are a minimal reproducible example. E Offline emfo wrote a day ago last edited by #5 @SGaist Thank you. I will find that information and post it here asap. E Offline emfo wrote about 12 hours ago last edited by emfo #6 We've reproduced the issue on the following combinations: Ubuntu 26.04, Linux 7.0.0, Quadro P2200, driver version 580.178 Ubuntu 26.04.1 LTS, Linux 7.0.0-38-generic, GeForce RTX 4060, driver version 595.99.02 In addition, we've seen the problem manifest on several other combinations of Ubuntu/Linux/graphics card/driver versions, with the only common factor being Qt. TimTom420 Online 5 unread TimTom420 Since the Xlib and XCB examples behave differently, it might help to check the EGL error immediately after the failed surface creation using eglGetError(). That could narrow down whether the problem is related to the native window handle or the EGL platform selection. It would also be useful to know the Qt version and whether forcing the XCB Qt platform plugin changes the result. If U R sad click here: https://www.youtube.com/watch?v=dQw4w9WgXcQ

Hi, QGLWidget has been deprecated in Qt 5 and removed in Qt 6. Are you really using that class ?

Thanks a lot for all this information. It has helped me get clarity on the questions that have been bugging me for weeks. I can now decide better what I want to do, and why. I will definitely share these with them ideas about unifying the UI for mobile and desktop with Qt, as it seems like it doesn't necessarily warrant replacing starting their application from scratch, only their UI code will get replaced (and its bindings).

This had been reported to Squish technical support team, and closed on behalf of the reporter. Unfortunately it was not possible to identify a clear cause so far.

[image: 01776ece-1308-4e3c-98fd-2749b3a4e221.png] Challenges faced: So when it came to building the d-pad, I was absolutely lost and was trying to approach this problem by drawing and arc instead and so I was reading about PathArc, and so it was getting so complicated, then I did see how it was implemented in the solution. repo: https://github.com/Meehir5907/QML-for-Beginners-Challenges/tree/Intro-Qt-Quick-My-Sol/StartingProject

@VikMorroHun said in blocked: cmake: command not found: In Linux I got more than 6000 hits How did you search to get 6000 hits?

@lacombe said in Création de fenêtres avec des widget: return QCoreApplication::exec(); QCoreApplication Class The QCoreApplication class provides an event loop for Qt applications without UI. ? QApplication a(argc, argv); ... return a.exec();

I had the same “You are not authorized” error when trying to create a Jira ticket. AlexBlasche’s fix works perfectly, use the direct login URL first