How to resolve this error ASSERT: “!”No style available without QApplication!“” in file kernel\qapplication.cpp, line 1054?

[Janilson Duarte]

When I start application to display a chart it presents me with this error:

QML debugging is enabled. Only use this in a safe environment. ASSERT: "!"No style available without QApplication!"" in file kernel\qapplication.cpp, line 1054 ASSERT: "!"No style available without QApplication!"" in file kernel\qapplication.cpp, line 1054

/file.pro

QT += quick
CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
        main.cpp

RESOURCES += qml.qrc

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

/file.cpp

```
#include <QGuiApplication>
#include <QQmlApplicationEngine>

 int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

QGuiApplication app(argc, argv);

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
    return -1;

return app.exec();
}

/file.qml

import QtQuick 2.9
import QtQuick.Window 2.2

import QtCharts 2.0
import QtQuick 2.0

Window {
visible: true
width: 640
height: 480
title: qsTr("Hello World")

ChartView {
    width: 400
    height: 300
    theme: ChartView.ChartThemeBrownSand
    antialiasing: true

    PieSeries {
        id: pieSeries
        PieSlice { label: "eaten"; value: 94.9 }
        PieSlice { label: "not yet eaten"; value: 5.1 }
     }
  }
}

[raven-worx]

@Janilson-Duarte
as the error says:
Instantiate a QApplication instead of a QGuiApplication in your main()

[J.Hilk]

@Janilson-Duarte
@raven-worx is right, you have to replace GuiApplication with QApplication, the reason for this is your use of QCharts

take a look at the docu

Note: Projects created with Qt Creator's Qt Quick Application wizard are based on the Qt Quick 2 template that uses QGuiApplication by default. All such QGuiApplication instances in the project must be replaced with QApplication as the module depends on Qt's Graphics View Framework for rendering.

Because QCharts is it's own modul, you'll prob also have to add QT += charts to your project file.

[Janilson Duarte]

Thank you very much guys, it worked.