Mcu 'rpi': Unable to connect The klippy host software is attempting to connect

Basic Information:

Printer Model: Voron2.4 350
MCU / Printerboard: BIGTREETECH-OCTOPUS-V1.0 Raspberry 4 Model B
moonraker (1).log (65.5 KB)
klippy.log (448.4 KB)

mcu ‘rpi’: Unable to connect
Once the underlying issue is corrected, use the
“FIRMWARE_RESTART” command to reset the firmware, reload the
config, and restart the host software.

Error configuring printer

After a few minutes
Printer is not ready
The klippy host software is attempting to connect. Please
retry in a few moments.

Fill out above information and in all cases attach your klippy.log file (use zip to compress it, if too big). Pasting your printer.cfg is not needed
Be sure to check our “Knowledge Base” Category first. Most relevant items, e.g. error messages, are covered there

Describe your issue:

I’ve tried all the options: updating firmware, changing cables, going through all the steps from the beginning, but nothing changes.

ls /dev/serial/by-id/*

Hello @Remi !

The issue is not your printer board, it’s your secondary mcu:

mcu 'rpi': Unable to open port: [Errno 2] No such file or directory: '/tmp/klipper_host_mcu'

Take care to not mix up the identifier:


[mcu host]
serial = /tmp/klipper_host_mcu

Have you setup the additional code?

pi@mainsailos:~ $ cd ~/klipper/
sudo cp ./scripts/klipper-mcu.service /etc/systemd/system/
sudo systemctl enable klipper-mcu.service

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.

[sudo] password for pi:
Created symlink /etc/systemd/system/ → /etc/systemd/system/klipper-mcu.service.
pi@mainsailos:~/klipper $ cd ~/klipper/
make menuconfig
Using default symbol values (no ‘/home/pi/klipper/.config’)
Configuration saved to ‘/home/pi/klipper/.config’
Creating symbolic link out/board
Loaded configuration ‘/home/pi/klipper/.config’
Configuration saved to ‘/home/pi/klipper/.config’
pi@mainsailos:~/klipper $ sudo service klipper stop
make flash
sudo service klipper start
Creating symbolic link out/board
Building out/autoconf.h
Compiling out/src/sched.o
Compiling out/src/command.o
Compiling out/src/basecmd.o
Compiling out/src/debugcmds.o
Compiling out/src/initial_pins.o
Compiling out/src/gpiocmds.o
Compiling out/src/stepper.o
Compiling out/src/endstop.o
Compiling out/src/trsync.o
Compiling out/src/adccmds.o
Compiling out/src/spicmds.o
Compiling out/src/sdiocmds.o
Compiling out/src/i2ccmds.o
Compiling out/src/pwmcmds.o
Compiling out/src/buttons.o
Compiling out/src/tmcuart.o
Compiling out/src/neopixel.o
Compiling out/src/pulse_counter.o
Compiling out/src/lcd_st7920.o
Compiling out/src/lcd_hd44780.o
Compiling out/src/spi_software.o
Compiling out/src/i2c_software.o
Compiling out/src/thermocouple.o
Compiling out/src/sensor_adxl345.o
Compiling out/src/sensor_angle.o
Compiling out/src/sensor_mpu9250.o
Compiling out/src/sensor_lis2dw.o
Compiling out/src/sensor_bulk.o
Compiling out/src/stm32/watchdog.o
Compiling out/src/stm32/gpio.o
Compiling out/src/stm32/clockline.o
Compiling out/src/stm32/dfu_reboot.o
Compiling out/src/generic/crc16_ccitt.o
Compiling out/src/generic/armcm_boot.o
Compiling out/src/generic/armcm_irq.o
Compiling out/src/generic/armcm_reset.o
Compiling out/src/…/lib/stm32f4/system_stm32f4xx.o
Compiling out/src/stm32/stm32f4.o
Compiling out/src/generic/armcm_timer.o
Compiling out/src/stm32/gpioperiph.o
Compiling out/src/stm32/adc.o
Compiling out/src/stm32/i2c.o
Compiling out/src/stm32/spi.o
Compiling out/src/stm32/sdio.o
Compiling out/src/stm32/usbotg.o
Compiling out/src/stm32/chipid.o
Compiling out/src/generic/usb_cdc.o
Compiling out/src/stm32/hard_pwm.o
Building out/compile_time_request.o
Version: v0.12.0-114-ga77d0790
Preprocessing out/src/generic/armcm_link.ld
Linking out/klipper.elf
Creating hex file out/klipper.bin
Building hid-flash
gcc -c -Wall -std=gnu99 -I . pkg-config libusb-1.0 --cflags main.c -o main.o
gcc -c -Wall -std=gnu99 -I . pkg-config libusb-1.0 --cflags hid-libusb.c -o hid-libusb.o
gcc -c -Wall -std=gnu99 -I . pkg-config libusb-1.0 --cflags rs232.c -o rs232.o
gcc -no-pie main.o hid-libusb.o rs232.o pkg-config libusb-1.0 --libs -lrt -lpthread -o hid-flash
Flashing out/klipper.bin to

Please specify FLASH_DEVICE

make: *** [src/stm32/Makefile:111: flash] Error 255

Please do not post just some fragment from which nobody sees what command you have issued and what has happened before the error

It just looks like you issued a wrong / not applicable make flash command that is not covered under the relevant documentation.