First Arduino Uno - Immediate Problems
On Linux "Permission Denied" generally means one of two things:


You're not in the dialout group (or you haven't logged out and logged in since), or
Something else is using the serial port.


For 1:

sudo usermod -a -G dialout ashley
&lt;log out or reboot&gt;


For 2:

The most common culprit is ModemManager. The simplest cure is to uninstall it:

sudo apt-get remove modemmanager