Cannot build Creator on Qt 6.1.0 with qmake

qtrob@rob-desktop:~/dev/g++-9.3.0/creator-5.0-6.1.0-qmake$ ls -a
.  ..
qtrob@rob-desktop:~/dev/g++-9.3.0/creator-5.0-6.1.0-qmake$ which qmake
/home/qtrob/dev/g++-9.3.0/qt-6.1.0-nowebengine-r/qtbase/bin/qmake
qtrob@rob-desktop:~/dev/g++-9.3.0/creator-5.0-6.1.0-qmake$ qmake ~/dev/src/creator-master-enterprise/qtcreator/qtcreator.pro CONFIG+=release DEFINES+=QTC_SHOW_BUILD_DATE && make
Info: creating cache file /home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/.qmake.cache
cd src/ && ( test -e Makefile || /home/qtrob/dev/g++-9.3.0/qt-6.1.0-nowebengine-r/qtbase/bin/qmake -o Makefile /home/qtrob/dev/src/creator-master-enterprise/qtcreator/src/src.pro CONFIG+=release DEFINES+=QTC_SHOW_BUILD_DATE ) && make -f Makefile 
Info: creating stash file /home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/.qmake.stash
make[1]: Verzeichnis „/home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/src“ wird betreten
cd shared/ && ( test -e Makefile || /home/qtrob/dev/g++-9.3.0/qt-6.1.0-nowebengine-r/qtbase/bin/qmake -o Makefile /home/qtrob/dev/src/creator-master-enterprise/qtcreator/src/shared/shared.pro CONFIG+=release DEFINES+=QTC_SHOW_BUILD_DATE ) && make -f Makefile 
make[2]: Verzeichnis „/home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/src/shared“ wird betreten
cd qbs/src/lib/scriptengine/ && ( test -e Makefile || /home/qtrob/dev/g++-9.3.0/qt-6.1.0-nowebengine-r/qtbase/bin/qmake -o Makefile /home/qtrob/dev/src/creator-master-enterprise/qtcreator/src/shared/qbs/src/lib/scriptengine/scriptengine.pro CONFIG+=release DEFINES+=QTC_SHOW_BUILD_DATE ) && make -f Makefile 
Cannot read /home/qtrob/dev/src/creator-master-enterprise/qtcreator/src/shared/qbs/src/shared/qtscript/src/3rdparty/javascriptcore/WebKit.pri: No such file or directory
Cannot read /home/qtrob/dev/src/creator-master-enterprise/qtcreator/src/shared/qbs/src/shared/qtscript/src/3rdparty/javascriptcore/JavaScriptCore/JavaScriptCore.pri: No such file or directory
sh: 1: /home/qtrob/dev/g++-9.3.0/qt-6.1.0-nowebengine-r/qtbase/bin/syncqt: not found
Project ERROR: Failed to execute syncqt for the bundled QtScript module.
make[2]: *** [Makefile:204: sub-qbs-src-lib-scriptengine-scriptengine-pro-make_first] Fehler 3
make[2]: Verzeichnis „/home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/src/shared“ wird verlassen
make[1]: *** [Makefile:53: sub-shared-make_first-ordered] Fehler 2
make[1]: Verzeichnis „/home/qtrob/dev/g++-9.3.0/creator-5.0-6.1.0-qmake/src“ wird verlassen
make: *** [Makefile:49: sub-src-make_first-ordered] Fehler 2
qtrob@rob-desktop:~/dev/g++-9.3.0/creator-5.0-6.1.0-qmake$