warning: libQt6DBus.so.6, needed by ..., not found (try using -rpath or -rpath-link)

nprobst

Hey there,
for almost two weeks I try to cross-compile Qt6 for RaspberryPi 3B+ running the newest RaspiOS Bookworm with Desktop.
As a Host Machine I'm running Ubuntu 22.04.

Configuring and Building QT6 with aarch64 cross compiler (also built from source to match gnu and glibc versions) worked but I now get the warning, when I try to Build a brand new QtQuick Project for RaspberryPi:

warning: libQt6DBus.so.6, needed by /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1, not found (try using -rpath or -rpath-link)

Followed by >100 Errors related to QDBus:

error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `QDBusMessage::type() const@Qt_6'
error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `operator<<(QDebug, QDBusMessage const&)@Qt_6'
error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `QDBusArgument::operator>>(double&) const@Qt_6'
error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `QDBusUnixFileDescriptor::QDBusUnixFileDescriptor(int)@Qt_6'
error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `QDBusPendingCall::error() const@Qt_6'
error: /home/niklas/haflinger/qt-raspi/lib/libQt6Gui.so.6.7.1: undefined reference to `QDBusPendingReplyBase::assign(QDBusPendingCall const&)@Qt_6'

LibQt6DBus does indeed exist in the lib folder:

niklas@niklas:~$ find /home/niklas/haflinger/qt-raspi/lib/libQt6DBus*
/home/niklas/haflinger/qt-raspi/lib/libQt6DBus.prl
/home/niklas/haflinger/qt-raspi/lib/libQt6DBus.so
/home/niklas/haflinger/qt-raspi/lib/libQt6DBus.so.6
/home/niklas/haflinger/qt-raspi/lib/libQt6DBus.so.6.7.1

D-Bus related output when building Qt6:

Qt modules and options:
  Qt Concurrent .......................... yes
  Qt D-Bus ............................... yes
  Qt D-Bus directly linked to libdbus .... no
  Qt Gui ................................. yes
  Qt Network ............................. yes
  Qt PrintSupport ........................ yes
  Qt Sql ................................. yes
  Qt Testlib ............................. yes
  Qt Widgets ............................. yes
  Qt Xml ................................. yes

Another thing to mention is that out of all the packages mentioned in the tutorials below,
the only thing I could not install (because my os is too new) was libgst-dev. (It was not found)

I've followed the steps mentioned in this tutorial:
https://wiki.qt.io/Cross-Compile_Qt_6_for_Raspberry_Pi
But compiled aarch64 toolchain with this:
https://github.com/MuyePan/CrossCompileQtForRpi

I hope you can help me, as I have no idea how to continue.

nprobst

Solved: I had to add Qt6::DBus like this:

target_link_libraries(untitledApp PRIVATE
Qt6::Core
..
..
..
Qt6::DBus
)

in the Projects CMakeLists.txt