QQmlApplicationEngine not completely unloading qml components

developa

I'm currently loading my main.qml using QQmlApplicationEngine and works fine, and then I want to switch to main2.qml (without calling quit() on my QQmlApplicationEngine since that triggers QCoreApplication::exit() which will exit my application). So I just delete my engine, make a new one and set the context properties again (not the same context properties for main.qml slightly different), and it loads fine. But I get warnings like

qrc:/qml/...: Unable to assign [undefined] to bool

Why is the engine not unloading and reloading the qml files again? Why do I get a warning for a property that was defined when I loaded the engine the first time but isn't defined when I load the second time.

NOTE: If I load main2.qml first, I don't get the warning, even though the property is undefined.

Your help is appreciated.

EDIT: Here is my code

QSharedPointer<QQmlApplicationEngine> m_engine;
QQmlContext* m_ctxt;

void loadEngine(int window){
    m_engine->clearComponentCache();
    m_engine.reset(new QQmlApplicationEngine, &QObject::deleteLater);
    m_ctxt = m_engine->rootContext();

    m_ctxt->setParent(m_engine.get());
    QVector<QQmlContext::PropertyPair> qmlProperties;

    qmlProperties.push_back(QQmlContext::PropertyPair{"object", QVariant::fromValue(object)});

    if(window == 1){
        qmlProperties.push_back(QQmlContext::PropertyPair{"object1", QVariant::fromValue(object1)});
        // add more context properties

        m_ctxt->setContextProperties(qmlProperties);
        m_engine->load(QUrl(QLatin1String("qrc:/qml/main.qml")));
    }
    else{    
        qmlProperties.push_back(QQmlContext::PropertyPair{"object2", QVariant::fromValue(object2)});
        // add more context properties

        m_ctxt->setContextProperties(qmlProperties);
        m_engine->load(QUrl(QLatin1String("qrc:/qml/main2.qml")));
    }
}

Mammamia

@developa said in QQmlApplicationEngine not completely unloading qml components:

void loadEngine(int window){
m_engine->clearComponentCache();

IIRC you should also call trimComponentCache https://doc.qt.io/qt-5/qqmlengine.html#trimComponentCache

void loadEngine(int window){
    m_engine->clearComponentCache();
    m_engine->trimComponentCache();