I generated a new project and wanted to use the same plate, material as in the previous. I made the mistake not to check the type of build plate selected. It was the default and not the one I wanted. (Mea culpa.)
After sending to the printer, the printer complained, that the build plate in the printer was not the same as in the g-code. Very good!
But I did not want to use an other plate. So I aborted the print, went back to studio, changed here the type of the plate, sliced again and sended it again to the printer.
To my surprise I got the same error message again.
So the g-code had not been updated.
(This time I simple continued the print and it succedded, but this was luck. Because likely the temperature would had been different.)
May be I should had made some dummy changes.