Permission denied on /dev/ttyACM0

Development Tools IDE 1.x
21

sudo chmod a+rw /dev/ttyACM0

I’m glad that command line fixed the problem for some but it didn't help me

Then I ran

sudo adduser yourUserName dialout

And the linux system reported that I’m already a member of dialout

Yet still on serial port in Arduino

“Serial port com1 not found”

22

sudo chmod a+rw /dev/ttyACM0 works for a single time

"sudo usermod -a -G dialout $USER" and "sudo usermod -a -G uucp $USER" neither work. still have to chmod everytime.

What am I missing? Obviously "USER" is changed to mine.
Thanks

23

sudo usermod -a -G dialout only works if you have a dialout group anyway. I had the same issue; The group did not exist and in that case adding a user to a non-existing group doesn't do anything

24

If the group dialout doesn't exist, do with the uucp group.
Moreover, create a /etc/udev/rules.d/50-myusb.rules or, if a 50-* file exists edit it and write at the end of:

KERNEL=="ttyUSB[0-9]",MODE="0666"
KERNEL=="ttyACM[0-9]",MODE="0666"

And re-login after.

That is all.

1 Like
25

BorjaLive:
The issue with the permissions for /dev/ttyACM0 can be permanantly solved by adding yourself to the dialout group. You will have to logout and then log back in before the group change is recognized.
You can do this with sudo usermod -a -G dialout $USER

Resource
It worked for me.

Worked for me! Many thanks!

26

anilkunchalaece:
try the following command

sudo chmod a+rw /dev/ttyACM0

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Check this link for more info https://www.youtube.com/watch?v=Z2hlBbZu3CI

Helped me too - security issue. Thanks