After updating latest kde with apt and reboot of system in runlevel 5, the system is hanging. Starting in runlevel 3 is working, so investigation was possible. Without earlykdm script runlevel 5 is working.

Found solution while googling: The preload statements in script have to contain a "<".

replace
if test "$1" = "start" && test -x /sbin/preload; then
   if test -z "$DISPLAYMANAGER_AUTOLOGIN"; then
      /sbin/preload /etc/preload.d/kdm
   else
      /usr/bin/ionice -n2 /sbin/preload /etc/preload.d/kdm.auto
      /usr/bin/ionice -n6 /sbin/preload /etc/preload.d/kde &
      echo $! > /var/run/preload-session.pid
   fi
fi

by
if test "$1" = "start" && test -x /sbin/preload; then
   if test -z "$DISPLAYMANAGER_AUTOLOGIN"; then
      /sbin/preload < /etc/preload.d/kdm
   else
      /usr/bin/ionice -n2 /sbin/preload < /etc/preload.d/kdm.auto
      /usr/bin/ionice -n6 /sbin/preload < /etc/preload.d/kde &
      echo $! > /var/run/preload-session.pid
   fi
fi