This gist demonstrates a bug in PyQt 5.5.1 (possibly 5.5.0 too) on Windows where explicitly destroying a dynamically created WebEngineView leads to a stack overflow crash on shutdown.

webenginetest.py

import sys

from PyQt5.QtCore import QUrl
from PyQt5.QtQuick import QQuickView
from PyQt5.QtWidgets import QApplication
from PyQt5 import QtWebEngineWidgets


if __name__ == "__main__":
    application = QApplication(sys.argv)

    view = QQuickView()
    view.setSource(QUrl.fromLocalFile('WebEngineTest.qml'))
    view.show()

    application.exec_()

WebEngineTest.qml

import QtQuick 2.5


Rectangle {
    width: 800
    height: 600
    color: "#eee"

    property var obj

    Text {
        text: "Load"
        anchors.left: parent.left

        verticalAlignment: Text.AlignVCenter
        horizontalAlignment: Text.AlignHCenter
        height: 100
        width: 100

        MouseArea {
            anchors.fill: parent
            onClicked: {
                console.log('Creating webengine')
                var component = Qt.createComponent('WebView.qml')
                if (component.status === Component.Ready) {
                    obj = component.createObject(root);
                    console.log(obj);
                }
            }
        }
    }

    Text {
        text: "Unload"
        anchors.top: parent.top
        anchors.right: parent.right

        verticalAlignment: Text.AlignVCenter
        horizontalAlignment: Text.AlignHCenter
        height: 100
        width: 100

        MouseArea {
            anchors.fill: parent
            onClicked: {
                if (obj) {
                    console.log('destroying')
                    obj.destroy()
                }
            }
        }
    }

    Rectangle {
        id: root
        anchors.fill: parent
        anchors.topMargin: 100
    }
}

WebView.qml

import QtWebEngine 1.1

WebEngineView {
    anchors.fill: parent
    url: "https://www.google.com"
}