Error with klipper connecting to moonraker

Basic Information:

Printer Model: Creality Ender 3 S1 pro
MCU / Printerboard:

…I am very new at this and I’m not sure why moonraker won’t connect to klipper, I’ve tried some stuff but I can’t make it work. The way I have it now it appears a message about moonraker that can’t connect to klipper and after some time another message appears about the mcu unable to connect.

klippy.log (86.5 KB)

Also, I’m using an old laptop with linux mint to run klipper

This is the screenshot

Have you had a look in your moonraker.log? You could also post it. From your klippy.log:

mcu ‘mcu’: Starting serial connect
mcu ‘mcu’: Unable to open serial port: [Errno 2] could not open port /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0: [Errno 2] No such file or directory: ‘/dev/serial/by-id/usb-1a86_USB_Serial-if00-port0’

Did you do Frequently Asked Questions - Klipper documentation Where’s my serial port?

Could also be this one Debian Bullseye Bug causing Klipper to no longer find the printer board

Good luck, hcet14

So, I did the thing of the Bullseye bug but at the end it still said the thing of No such file or directory when I wrote “ls /dev/serial//by-id/*”
And here is the moonraker.log

That’s your setup?

Yes, but I use mainsail on both depending on the moment and I usually use the laptop for writing commands in linux instead of ssh

You can upload logs directly into your posts.
No need for external hoster.

Yeah, but because it was more than 8mb it didn’t let me

Textfiles can be zipped properly.
Just for the next time.

Are you sure that’s according to Klipper? Does it make sense to use Mainsail also on your host (old laptop with linux mint)?

I mean that I have it in the old laptop but to use it I use the web browser in the in the laptop and pc

Not sure what the current status is. If the issue still exists, then show the output of:

apt-cache policy udev


  1. Disconnect the board from the laptop
  2. Reconnect it
  3. sudo dmesg > dmesg.txt and attach the dmesg.txt file here

I don’t really understand the part of disconnecting the board, because the laptop alone has the issue, but I still ran what you put and got the file
dmesg.txt (69.6 KB)

Is my understanding correct:

  • The Laptop is running Linux Mint
  • Klipper is installed and running on the Laptop
  • Your printer board is connected to the Laptop via USB

I mean yes, but since the problem is in the laptop and connecting the printer hasn’t done much I just keep it unpluged till I fix the problem

To ensure we are on the same page: Do you understand that Klipper requires a continuous connection to the host (e.g., your laptop) to function? The issue does not lie solely with the laptop. If anything, it is a combination of the way the host and the printer board interact.


  1. Turn on the printer.
  2. Connect the printer board to your laptop.
  3. Run sudo dmesg > dmesg.txt in the command prompt, and then attach the ‘dmesg.txt’ file here.

Perform these steps in the exact sequence provided.

Okay, so I’ve done what you told me and got the file
dmesg.txt (67.1 KB)

Follow Other Single Board Computers (SBC) apart from Raspberry Pis, namely the last point about BRLTTY and ModemManager