I'm using an Ubuntu 14.04 and I'm having trouble with port permission for /dev/ttyACM0 . Every time I plug in my arduino uno board to my laptop, I face problems uploading code to the board beacuse I get a 'Permission Denied' error.

The problem was resolved when I gave the port Read-Write access with sudo chmod 666 /dev/ttyACM0, but only temporarily. The permission error reoccurs when I disconnect and reconnect the arduino board.

I followed this thread to make the change permanent by adding my username to the dialout group, but it didn't work.

Is there any other way to resolve this issue??

  • 1
    The arduino website actualy has step by step instructions on how to fix this problem. it is displayed under the Getting started > linux page at the bottom. Here is the link for quick access. https://www.arduino.cc/en/Guide/Linux
    – user638828
    Jan 5, 2017 at 21:37

1 Answer 1


add yourself to the dialout group, as described in thread you mentioned, then log out and back in. Now it should work. This is because the modification won't take effect until your current session is closed and a new one is started.

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    Original post seems to state user already added to dialout group and sudo chmod 666 /dev/ttyACM0 only works temporarily. I'm also looking for a solution and have tried both of these approaches. Apr 21, 2016 at 7:36
  • Does not work on 14.04 or 16.04, Cannot access despit ethe user being present on dialout group
    – ArunMKumar
    May 13, 2017 at 22:24

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