avrdude: Error: butterfly programmer uses avr_write_page() but does not provide a cmd() method
After much frustration in trying things, I came across this forum post which advised:

sudo systemctl stop ModemManager.service


If this works, disable the service from starting next boot:

sudo systemctl disable ModemManager.service


It seems like setting ENV{ID_MM_DEVICE_IGNORE}="1" in a udev rule is insufficient.