New Atmega32U on Arduino due doesn't work

I just have a new Arduino due board and I swaped the on board Atmega32U Chip with a brand new on out of curiosity. However, the programming doesn't work anymore.
Should I bootload the new Atmega32U before programming? In the datasheet It seems like to have a bootloader pre-installed. So I'm getting a bit confused.
Can anyone have some guess?


AFAICT, there is a 16U2 on a DUE board aside the Sam3x....

What is the "correct firmware"? Does Arduino provide it?

You need to program the 32u with the correct firmware.


look for IDE GitHub - MCUdude/MightyCore: Arduino hardware package for ATmega1284, ATmega644, ATmega324, ATmega324PB, ATmega164, ATmega32, ATmega16 and ATmega8535

Best regards.