If you create an application described in https://bugreports.qt.io/browse/QTBUG-50074 and call getA from another web client (other browser or other tab, ..) and then reload the webpage and try to change a property of the object that you get from getA the qt application crashes or the values are not updated anymore. Also when you call the getA from the other client you get wrong initial property values of that object if the values changed since the object was first requested with getA. My temporary solution would be to change in QJsonValue QMetaObjectPublisher::wrapResult(... starting from row 564

Q_ASSERT(object == wrappedObjects.value(id).object);

// check if this transport is already assigned to the object

if (transport && !wrappedObjects.value(id).transports.contains(transport))         wrappedObjects[id].transports.append(transport);

classInfo = wrappedObjects.value(id).classinfo;

to

Q_ASSERT(object == wrappedObjects.value(id).object);

// check if this transport is already assigned to the object

if (transport && !wrappedObjects.value(id).transports.contains(transport)) { wrappedObjects[id].transports.append(transport);

transportedWrappedObjects.insert(transport, id);

}

classInfo = classInfoForObject(object, transport);

I cannot trace the bug so I cannot tell you where it crashes exactly but it is easy to reproduce.