Cura 21.00 Error: Failed to autodetect serial port. Solved.

My google foo has failed me.

I usually print using the SD card on my TAZ 6, but I wanted to upgrade the firmware. Not finding any way to do this using the SD card, I dragged my printer across my house to my computer (much easier to move than my computer).
I’m running Linux Mint 18.

At first I thought that cura did not see the printer as attempting to upgrade the firmware got me to a screen asking me to plug in and turn on my printer. I verified that lsusb could see the printer, then I noticed that the “save STL” icon hand changed to “control”, but it was grayed out. After starting cura connecting my printer and power up my printer in many different orders, I thought to load an object into cura. Suddenly the “control” icon was no-longer grayed!

Clicking on “Conrol” brought up the control window, and in the title bar, there was the error message in the title of this post. (wouldn’t in have been nice to get this error message a bit sooner?)

Anyway searching on that error message only got me threads about older and different linux versions running older versions of Cura.

What is my next step? How do I force cura to properly detect my printer?

Edit: I found there was an error log. In it I found the following:
Unexpected error while connecting to serial port: /dev/ttyACM0 SerialException: ‘[Errno 13] could not open port /dev/ttyACM0: [Errno 13] Permission denied: ‘/dev/ttyACM0’’ @
Found no ports to try for auto detection
Changing monitoring state from ‘Opening serial port’ to ‘Error: Failed to autodetect serial port.’
So somehow, cura does not have permission to open a serial port. How does one give it permission?

***Edit: I figured it out. I needed to add myself to the “dialout” group. This gave me and Cura Permission to access the serial port.

Glad you got it figured out. Yes, on Linux systems (and Ubuntu and Debian based systems included) you need to be added to the dialout group. If you are not in the dialout group running Cura under sudo will bypass this error and allow cura to access the serial port, but it’s kindof a pain.

The same thing happens with the Arduino IDE and programming Arduino boards. Since the RAMBO boards that the Lulzbot machines run off are really just glorified Arduino chips with motor controllers built-in this makes sense that this behavior would be the same for CURA.