Can't connect to serial port I'm trying to make my Arduino's LED blink for the first time, but when I try to upload the code I get the following error in the Serial Monitor:


  Error opening serial port '/dev/ttyACM0'.
  Try consulting the documentation at http://playground.arduino.cc/Linux/All#Permission


BTW, I have serial.debug_rate=9600, so I don't think that's the problem. Can anyone help me with this please?
It seems your serial does not have the right permissions to be opened in user mode. Try adjusting that by typing

sudo chmod a+rw /dev/ttyACM0


on the console (open it by CTRLALTT).