Solution: avrdude: ser_open (): can't open device on Arduino

In this article I will explain how to solve a common error in Arduino:

avrdude: ser_open (): can't open device "/ dev / ttyACM0": Permission denied

Background

After a long time without using Arduino I have taken my two inserts (the original and the elegoo) to do some activities with my daughter. I connect them, I am going to insert the blink to see that everything is fine and when I go to send it to the board it returns the well-known error.

Arduino: 1.8.5 (Linux), Card: "Arduino / Genuino Uno" avrdude: ser_open (): can't open device "/ dev / ttyACM0": Permission denied Problem uploading to the board. Visit http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

Both on my PC and my laptop I have Ubuntu 18.04 installed.

Solution

I start by following the link that they suggest. And I follow the steps

En tools / plate Arduino / Genuino Uno is selected

En tools / serial port / dev / ttyACM0

and as the documentation suggests, in case there are problems with the Drivers and permissions, I open the terminal and execute:

 sudo usermod -a -G tty yourUserName
 sudo usermod -a -G dialout yourUserName

where yourUserName is your username

Now I log out and log in again. And just in case I restart the PC / laptop.

It still doesn't work for me and the Arduino documentation doesn't help anymore. So I've kept looking, in forums and blogs. If at this point it does not work for you and you are like me. Follow the next steps

ls / dev / ttyACM0 returns / dev / ttyACM0
ls -l / dev / ttyACM0 returns crw-rw—- 1 root dialout 166, 0 Nov 26 16:41 / dev / ttyACM

With this we confirm that the port exists

We are going to give permissions and check if our user has the necessary permissions.

 sudo chmod a+rw /dev/ttyACM0
 id devuelve 20(dialout) 

And I see that the user is within the group dial out so this part we got it right.

What has worked for me has been to reinstall Arduino.

If you check

which avrdude

And it does not return anything reinstalling Arduino should be fixed.

sudo apt install --reinstall arduino

And if you have not been able to solve the problem, leave me a comment and I will try to help you.

AVRDUDE Troubleshooting Tool

There is a script they have prepared to fix this problem. You can try to see if it helps you. I have not used it but I leave it because I think it can be a useful resource.

AVRDUDE

I leave a bit of information to better understand what AVRDUDE is. The name comes from AVRDUDE - AVR Downloader / UploaDEr

AVRDUDE is a utility to download / load / manipulate the ROM and EEPROM contents of AVR microcontrollers using the in-system programming (ISP) technique.

https://www.nongnu.org/avrdude/

AVRDUDE was started by Brian S. Dean as a private project as a programmer for the Atmel AVR series of microcontrollers.

You can find the software and much more information in the project website.