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?


2 Answers 2


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).


That issue is due to your username not being in the dialout group. Try: sudo usermod -a -G dialout yourusername and rebooting to load the changes, then check again if the problem still persists...

I wrote an article about that here: Solving Arduino IDE upload problem, and serial monitor error on Ubuntu.

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