Updating Ultimaker 2+ firmware using Cura 2.5.0 on Linux / Ubuntu 16.04

[xenomachina 0]

I have an Ultimaker 2+. I've updated the firmware in the past, but recently I couldn't get it to work. I was eventually able to fix it, and thought I should post the solution here for others who run into the same roadblock.

My computer is running Ubuntu 16.04, and I'm using Cura 2.5.0. I go to Settings > Printer > Manage Printers..., and click "Upgrade Firmware" and finally "Automatically upgrade Firmware". It says "Starting firmware update, this may take a while", and then about a second later fails with "Firmware update failed due to a communication error".

First, this is a terrible error message, as it does not provide enough info to actually diagnose the problem. I ended up figuring out what it was by running Cura in a terminal and looking at what it dumped there. Cura should look at errno and use that to produce a more meaningful error message.

Second, why does firmware update have to be over USB? Why can't it be via SD card? I keep my printer far away from my computer, and it's pretty annoying having to lug it over whenever Cura says there's an update, not to mention debugging the issues that frequently crop up.

Finally, the "communication error" is due to a permissions issue. Regular users on Ubuntu (and possibly other Linux distros) don't have access to serial devices unless in the

dialout

group. To fix this problem, run:

sudo usermod -a -G dialout $USER

You may need to log out and log back in for this to actually take effect.