Error message makes it sound like the wrong "serial" port is being selected.
Are any of the connections to d0,d1, and reset?
If not, connections to 5v might suggest whatever you have connected is drawing enough load to trip up the 328s reset.
Error message makes it sound like the wrong "serial" port is being selected.
Are any of the connections to d0,d1, and reset?
If not, connections to 5v might suggest whatever you have connected is drawing enough load to trip up the 328s reset.