Cannot get QDBusConnection to work

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1

Hello! I’m trying to build a simple app that uses QDBusConnection to connect to the system dbus and listen for calls from other processes. I tried mixing up this guide and this SA question, and here’s the result:

main.cpp

#include <QCoreApplication>
#include <QDebug>
#include <QtDBus/QtDBus>
#include "background.h"

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    qWarning() << "daemon started!";

    Background *e = new Background;
    e->setupDBus();

    qWarning() << "daemon initialized";
    return app.exec();
}

background.h

#ifndef BACKGROUND_H
#define BACKGROUND_H

#include <QCoreApplication>
#include <QDebug>
#include <QtDBus/QtDBus>

#include <QObject>

class Background : QObject
{
    Q_OBJECT
    Q_CLASSINFO("D-Bus Interface", "org.foo.Background")

public:
    Background(){

    }

    void setupDBus()
    {
        QDBusConnection session = QDBusConnection("org.foo.Background");

        if (!session.isConnected())
        {
            qWarning("Cannot connect to the D-Bus session bus.");
            //return;
        } else {
            qWarning("successfully connected to the D-Bus session bus.");
        }

        session.connect("", "/", "org.foo.Background", "slot_foo", this, SLOT(slot_foo));

        if(!session.registerObject("/", this, QDBusConnection::ExportScriptableContents)) {
            qWarning  ("Cannot registerObject 1.");
           // return;
        } else {
            qWarning  ("done registerObject 1.");
        }

        if(!session.registerService("org.foo.Background")) {
            qWarning ("Cannot registerObject 2.");
           // return;
        } else {
            qWarning ("done registerObject 2.");
        }

        if (!session.isConnected())
        {
            qWarning("Cannot connect to the D-Bus session bus.");
            //return;
        } else {
            qWarning("successfully connected to the D-Bus session bus.");
        }
    }

Q_SIGNALS:

public Q_SLOTS:
    Q_SCRIPTABLE void slot_foo()
    {
        qDebug() << "request received";
    }

protected Q_SLOTS:
    void dbusCanNotSeeMe(){}
};
#endif // BACKGROUND_H

/usr/share/dbus-1/interfaces/org.foo.Background.xml

<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
  <interface name="org.foo.Background">
    <method name="slot_foo">
    </method>
  </interface>
</node>

it builds correctly but when run, each of the if statement fails:

daemon started!
Cannot connect to the D-Bus session bus.
Cannot registerObject 1.
Cannot registerObject 2.
Cannot connect to the D-Bus session bus.

what am I doing wrong?

thanks in advance!