I am following the tutorial of Prusa for using Octoprint with my Prusa i3 MK3. I have a Raspbery Pi Zero and I'm using the built-in GPIO pins, not an USB connection.

  • Wifi works. I can reach the Raspberry via HTTP and SSH
  • I have enabled [RPi Port] via the i3 menu

But in the Octoprint website, there's no serial port to select. It just shows "AUTO" and after a while it displays an error message that there's no Serial port found.

Via SSH I can find quite some devices which look like Serial:

  • /dev/serial1
  • /dev/tty#, where # is a number
  • /dev/ttyAMA0
  • /dev/ttyprintk

I haven't had any issues with Serial connection since 2019 and despite all warnings, the Pi Zero did a great job. However, after the last Octoprint update, Octoprint didn't come up any more, so I did a reinstall from scratch.

I'm using OctoPrint 1.9.0


1 Answer 1


Neither the tutorial of Prusa nor the Octoprint setup instructions mention this. But it's common Raspberry Pi knowledge, for everyone how experiments with the RPi.

The Serial interface that works over GPIO needs to be activated via

sudo raspi-config

In the menu, go to "Interface Options" (3), then "Serial Port" (I6). Answer "No" for the login shell and "Yes" for the Serial port hardware. After that, reboot your Raspberry when being asked.

The Octoprint web interface should then detect /dev/ttyS0 and be able to connect.

  • 1
    $\begingroup$ I really wish you would have added just a tiny bit of detail here. For example... "In the menu"... - In the menu of what? I have been scouring every menu I can find for octoprint / PUTTY and absolutely nowhere is there an "interface options" or "Serial Port". I have no idea what the (3) or (I6) is referencing. This seems like the info I need but the vagueness leaves me with more questions than answers. $\endgroup$
    – abiss221
    Nov 17, 2023 at 13:19
  • $\begingroup$ @abiss221 - Thomas is referring to the menu(s) of the command line tool raspi-config. $\endgroup$
    – Greenonline
    Nov 17, 2023 at 13:47
  • 1
    $\begingroup$ Thomas, please don't forget to check your answer as the "accepted answer". $\endgroup$
    – Greenonline
    Nov 17, 2023 at 14:35

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