Problem uploading to NANO board.

What is this?

avrdude: stk500_paged_write(): (a) protocol error, expect=0x14, resp=0x64 avrdude: Send: V [56] @ [40] . [00] . [00] . [0c] [20] avrdude: Recv: avrdude: stk500_cmd(): programmer is out of sync processing.app.debug.RunnerException...... ............................................. ..........................................

Thanks in avance

Wrong board selected? Wrong bootloader installed? Incorrect wiring? Auto-reset not working? Serial output flooded by previous sketch?

Try holding down the Reset button, unplugging and re-plugging the USB cable, starting the upload, and releasing RESET when the "Binary sketch size:" message appears.