Printing does not start because of the Bulid Plate

Hello guys,

when I upload a print job, the screen says “Prepairing Print” (it takes too long as usual), then it just says “Error, Error to starting print”".

On the main screen it says that I should clean the bulid plate, I go to this menu item, say that the build plate is inserted and cleaned. Before printing, the printer says that everything is OK, when starting a print, the same message always appears and in the main menu it asks for the build plate again.

Now I have ordered a new build plate, although I know that there are no sensors in it, but the error is still there. I have downgraded the firmware to 2.3.0. I can’t think of anything else, can anyone help me?

Thank you very much.