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QML Application stucks at Windows 10

  • Hello all!

    I have the following issue: one of my C++ applications is developed for Linux and Windows system. Both applications is working well on others PC's after deploying with windeployqt and linuxdeployqt. But I have the following behaviour on one of Windows 10 machines. Application stucks when main window is appearing, I have no errors in the console so I could not find any solution.
    So my question is: how could I fix this issue and what should I check for finding any possible reason? I use 5.14.1, maybe should I try something older?

    Thank you in advance.

  • Lifetime Qt Champion

    @St-Stanislav You could try to remove/disable functionality in your app until it works. Then you would know which part of it causes this behaviour.

  • Moderators

    Hi @St-Stanislav and welcome

    Application stucks when main window is appearing

    what does that mean exactly, can you give some more details?

    I'll have to ask, because I noticed strange behavior in a fringe case as well:
    Is the Windows10 machine a VM ?

  • @jsulm Thank you for answer, this is a good approach, but this is no my machine, so I could not permanently run and check cropped versions in the nearest future.

  • @J-Hilk So I could try to describe what I have seen: application starts (in the console log I could see only my messages and everything is ok, like on a working machine), main window appears (it is a fully blank), mouse pointer starts turning and "thinking" and then applications just closes without errors.

    No, it is not a VM, this Windows with version 1909 (build 18363.693)

  • Moderators

    I assume it's working on other Win 10 machines ?

    I had something similar where my app would crash during Bluetooth scans (on Windows pcs)

    My crystal ball is rather dull here 🤷‍♂️ You'll have to narrow it down somehow

  • @J-Hilk I will try to do my best to give more information: I am scanning USB devices after loading application (I am using libusb for both systems), so maybe this could be a weak point, but it is very strange that I have no problem with other Windows 10 machines.

  • Hi,
    just wild guess but maybe there is something connected to the usb on this particular machine that libusb have issues with? Ideal testing scenario is unplug everything and then start connecting one by one.

    My experience with USB devices is somehow limited to the barcode scanners - which either run as HID devices and there is nothing I need to do or emulated serial devices, which I can fully service by QSerialPort.

  • Maybe the wrong direction but we encounterd problems with qml application if the maschine is connected to a docking station. There are running some USB-Display drivers not capable of displaying openGl needed by qml.

  • After some experiments I have found that problem is only with QML-interface: I had disabled all backend code and found that some pages (I use SwipeView) crash application. Now I am trying to understand what exactly could be the reason...

  • My researching lead me to the following point: looks like that issue consist of videodrivers and opengl. I have situation when my application craches approximately 1 of 3 times. The machine where problem was occured has internal video card on motherboard Gigabyte h55m-s2, I have tried to change drivers and get the strange behavior, when application starts well, but colors are not normal. So I will continue my investigation to this direction.

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