QDesktopServices::open - kf.windowsystem: Could not find any platform plugin

r3d9u11

Hello.
I've faced the trouble, I can't run any local file within QDesktopServices::open or QProcess::startDetached.

Text of the exception:

kf.windowsystem: Could not find any platform plugin
This application failed to start because it could not find or load the Qt platform plugin "xcb"
in "".

Available platform plugins are: xcb.

Reinstalling the application may fix this problem.

I've tried:

#include <QApplication>
#include <QUrl>
#include <QDesktopServices>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv); // just this line
    QDesktopServices::openUrl(QUrl::fromLocalFile("/home/user/myfile.pdf"));
    return app.exec();
}

or

QProcess::startDetached("xdg-open", QStringList() << "/home/user/myfile.pdf");

in all cases I have the same exception.

I have already installed all needed packages:

sudo apt-get install libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev libxcb-shape0-dev libxcb-xkb-dev

Tested on Ubuntu (KDE) 20.04, Qt 5.15.2

What is wrong?
Thanks!

r3d9u11

the touble is in option

Project -> Run -> [x] Add build library search path to LD_LIBRARY_PATH

if uncheck it, all works fine under QtCreator,
and problem is gone

r3d9u11

The problem rises only when try to launch application from QtCreator (Run/Debug). If try to launch compiled binary file, so it works fine.

r3d9u11

the touble is in option

Project -> Run -> [x] Add build library search path to LD_LIBRARY_PATH

if uncheck it, all works fine under QtCreator,
and problem is gone