<![CDATA[Wayland : Creating a fake screen in order for Qt not to crash]]>I'am having a trouble turning on off screen on wyaland .
Using these commands on my RPI5, ( using labwc)

  • wlr-randr --output HDMI-A-1 --on
  • wlr-randr --output HDMI-A-1 --off
    Makes my app crash the last log i can see as important is ;
QCoreApplication::postEvent: Unexpected null receiver
qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
MainWindow::processExited Le processus NeoScheduler a termine par lui-meme

Is there any solution ? is it a known issue ?
Thank you

]]>https://forum.qt.io/topic/164482/wayland-creating-a-fake-screen-in-order-for-qt-not-to-crashRSS for NodeFri, 24 Apr 2026 15:23:22 GMTTue, 24 Mar 2026 13:08:14 GMT60<![CDATA[Reply to Wayland : Creating a fake screen in order for Qt not to crash on Wed, 25 Mar 2026 13:12:03 GMT]]>@The-Qt-Mayssa
I think we're talking in circles.
If you want someone in the forum to analyze the problem, you need to provide a minimal reproducer. In the unlikely case that it's a bug in Qt, it won't be fixed in an EOL version.
You will have to upgrade at some point anyway.

]]>https://forum.qt.io/post/837322https://forum.qt.io/post/837322Wed, 25 Mar 2026 13:12:03 GMT<![CDATA[Reply to Wayland : Creating a fake screen in order for Qt not to crash on Wed, 25 Mar 2026 13:00:26 GMT]]>@Axel-Spoerl Passing to qt6 , is more complicated then that. The idea is to keep app working , fixing some bugs ( the eolution to qt6 is not an option today :// )
i start the app manually via a script launch.sh , that sets the exports values then ./myapp.

Knowing the app crashes only when doing wlr-randr command to turn on off screen.
I already added logs to debug ( since i'm cross compiling to deploy on a light version of tirixie :') ) , i'm getting this as a last log


2026.03.25 13:16:08 Creating a fake screen in order for Qt not to crash
2026.03.25 13:16:08[D] step Primary screen changed: QScreen(0x73a0270, name="")
2026.03.25 13:16:08[D] step Screen removed: QScreen(0x6ec0510, name="HDMI-A-1")

the code:

    QObject::connect(&app, &QGuiApplication::screenRemoved,
                     [](QScreen *screen){
                         qDebug() << "step Screen removed:" << screen;
                     });

    QObject::connect(&app, &QGuiApplication::primaryScreenChanged,
                     [](QScreen *screen){
                         qDebug() << "step Primary screen changed:" << screen;
                     });
]]>https://forum.qt.io/post/837321https://forum.qt.io/post/837321Wed, 25 Mar 2026 13:00:26 GMT<![CDATA[Reply to Wayland : Creating a fake screen in order for Qt not to crash on Wed, 25 Mar 2026 12:20:02 GMT]]>Well, that's not a reproducer.
It's how you start the app that crashes.
However, Qt 5.15 has been EOL for a long time.
The wayland implementation has been hardened recently.
Please use Qt 6.8 or later.

]]>https://forum.qt.io/post/837319https://forum.qt.io/post/837319Wed, 25 Mar 2026 12:20:02 GMT<![CDATA[Reply to Wayland : Creating a fake screen in order for Qt not to crash on Wed, 25 Mar 2026 08:52:54 GMT]]>Hello @Axel-Spoerl ,

I’m running a Qt Widgets application on Wayland (Raspberry Pi 5, wlroots-based compositor).
Qt version : 5.15.17

The app is started with:

export QT_QPA_PLATFORM=wayland
export WAYLAND_DISPLAY=wayland-0
./myApp

When I disable the display using:

wlr-randr --output HDMI-A-1 --off

the application crashes or becomes unstable.

This also happens when the command is executed via SSH.

When I re-enable the output:

wlr-randr --output HDMI-A-1 --on

the issue still occurs.

It seems that removing the output entirely from Wayland causes Qt to crash.

Questions:

  • Is this a known limitation of Qt Widgets on Wayland?
  • What is the recommended way to handle display power management in this setup?
  • Should outputs be avoided from being fully disabled when using Qt?

Thanks for your help.

]]>https://forum.qt.io/post/837314https://forum.qt.io/post/837314Wed, 25 Mar 2026 08:52:54 GMT<![CDATA[Reply to Wayland : Creating a fake screen in order for Qt not to crash on Tue, 24 Mar 2026 15:16:16 GMT]]>Hi, @The-Qt-Mayssa ,
can you please post a minimal compilable reproducer?

]]>https://forum.qt.io/post/837301https://forum.qt.io/post/837301Tue, 24 Mar 2026 15:16:16 GMT