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Common Error Messages

mcu 'xxx': Unable to connect​

  1. Error Message

  2. Error Cause

    • Host machine cannot find the main board and connect

  3. Solution

    • Check Klippy.log and scroll to the bottom
    • If [Errno 2] appears, it means the search ID has not been found and added to printer.cfg
    • If serialhdl.error: mcu 'xxx': Serial connection closed appears, it means the CAN ID has not been found or is filled incorrectly. You need to search for the ID and fill it in.
    • If mcu 'mcu': Unable to open CAN port: [Errno 19] No such device appears, it means there is no UOTC or a motherboard with a CAN bridge flashed

    • If mcu 'mcu': Unable to open CAN port: Failed to transmit: [Errno 100] Network is down appears, it means CAN network is not configured or CAN0 is not started

    • If mcu 'mcu': Unable to open CAN port: Failed to transmit: [Errno 105] Network is down appears, it means CAN network's buffer is too small. The solution is to increase the buffer size.

    • If [Errno 105] Network is down and [Errno 100] Network is down appear, you can refer to this document here: CAN Configuration

mcu 'mcu': Invalid CAN uuid​

  1. Error Message

  2. Error Cause

    • CAN ID is not filled in or filled incorrectly

  3. Solution

    • Need to search for the ID and fill it in

Option 'serial' in section 'mcu' must be specified​

  1. Error Message

  2. Error Cause

    • USB ID is not filled in or filled incorrectly

  3. Solution

    • Need to search for the ID and fill it in

homing override method always homes X and Y before homing Z. The safe_z_home​

  1. Error Message

  2. Error Cause

    • [safe_z_home] and [homing_override] are configured repeatedly

  3. Solution

    • Only one of them needs to be configured; delete the other one

Error ‘XXX ‘mcu’ shutdown: ADC out of range….​

  1. Error Message

  2. Error Cause

    • Klipper detects that the temperature exceeds the maximum or minimum threshold (the thermistor may be open-circuited or short-circuited), and the system will enter shutdown protection mode.

  3. Solution

    • Search for min_temp: in the configuration and change the minimum temperature to -235
    • Search for max_temp: in the configuration and change the maximum temperature to 99999999
    • Check if the thermistor model is correct
    • Check if the thermistor pin is correct
    • Check if the thermistor is short-circuited
    • After determining and solving the issue, revert back to the original temperature settings

MCU ‘mcu’ shutdown: Timer too close​

  1. Error Message

  2. Error Cause

    • Mainly due to overload on the lower-level machine or timeout on the upper-level machine

  3. Solution

    • Decrease microstepping
    • Reduce printing speed
    • Re-flash the upper-level system and re-flash the firmware

Raspberry Pi can use this method​

sudo timedatectl status | grep "NTP service" 
sudo timedatectl set-ntp false
  • Check NTP service status
  • Turn off NTP synchronization

Communication timeout during homing probe​

  1. Error Message

    No image available

  2. Error Cause

    • CAN and screen service running simultaneously is likely to cause this error

  3. Solution

    • Use SSH to connect to the upper-level machine over the network and execute the following command
    • If Klipper is updated, it will automatically revert
    • Do not execute during printing
    sed -i 's/TRSYNC_TIMEOUT = 0.025/TRSYNC_TIMEOUT = 0.05/g' ~/klipper/klippy/mcu.py && sudo systemctl restart klipper