Common Error Messages

mcu 'xxx': Unable to connect

1. Error Message

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2. Error Cause

   • The host computer cannot find and connect to the mainboard.

3. Solution

   • Check the bottom of Klippy.log.
   • If [Errno 2] appears, it means the ID was not searched for and added to printer.cfg.
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   • If serialhdl.error: mcu 'xxx': Serial connection closed appears, it means the CAN ID was not found or entered incorrectly. You need to search for the ID and enter it.
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   • If mcu 'mcu': Unable to open CAN port: [Errno 19] No such device appears, it means there is no UOTC or a mainboard flashed with CAN bridge firmware.
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   • If mcu 'mcu': Unable to open CAN port: Failed to transmit: [Errno 100] Network is down appears, it means the 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 the CAN network buffer is too small. Solution: Increase the buffer size.

   • For [Errno 105] Network is down and [Errno 100] Network is down, refer to this documentation: CAN Configuration.

mcu 'mcu': Invalid CAN uuid

1. Error Message

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2. Error Cause

   • CAN ID is not filled in or is entered incorrectly.

3. Solution

   • You need to search for the ID and enter it.

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

1. Error Message

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2. Error Cause

   • USB ID is not filled in or is entered incorrectly.

3. Solution

   • You need to search for the ID and enter it.

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

1. Error Message

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2. Error Cause

   • Duplicate configuration of [safe_z_home] and [homing_override].

3. Solution

   • Only configure one of them and delete the other.

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

1. Error Message

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2. Error Cause

   • Klipper detected a temperature exceeding the maximum or minimum threshold (thermistor may be open or shorted). The system will enter shutdown protection mode.

3. Solution

   • In the configuration, search for min_temp: and change the minimum temperature to -235.
   • In the configuration, search for max_temp: and change the maximum temperature to 500.
   • Check if the thermistor model is correct.
   • Check if the thermistor pin is correct.
   • Check if the thermistor is shorted.
   • After confirming and resolving the issue, change the temperatures back to their original values.

MCU ‘mcu’ shutdown: Timer too close

1. Error Message

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2. Error Cause

   • Mainly caused by the microcontroller being overloaded or the host computer timing out.

3. Solution

   • Reduce microstepping.
   • Decrease printing speed.
   • Reflash the host system and reflash the firmware.

For Raspberry Pi, you can use this method

sudo timedatectl status | grep "NTP service"
sudo timedatectl set-ntp false

• Check NTP service status.
• Disable NTP synchronization.

Communication timeout during homing probe

1. Error Message

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2. Error Cause

   • Running CAN and screen services simultaneously is likely to cause this error.

3. Solution

   • Use SSH to connect to the host computer over the network and execute the following code.
   • If Klipper is updated, it will automatically revert.
   • Do not execute this during printing.

   sed -i 's/TRSYNC_TIMEOUT = 0.025/TRSYNC_TIMEOUT = 0.05/g' ~/klipper/klippy/mcu.py && sudo systemctl restart klipper