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Common Error Prompts

Connection Issues​

mcu 'xxx': Unable to connect​

Error Message: The host computer cannot find or connect to the motherboard.

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Error Cause: The Klipper host computer cannot establish communication with the motherboard, which may be caused by multiple reasons.

Solutions: First, check the Klippy.log file and scroll to the bottom. Take appropriate measures based on the specific error message:

  1. [Errno 2] error: Indicates that the found device ID has not been added to the printer.cfg file.

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  2. serialhdl.error: mcu 'xxx': Serial connection closed error: Indicates that the CAN ID was not found or was entered incorrectly. Re-search for the ID and fill it in correctly.

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  3. mcu 'mcu': Unable to open CAN port: [Errno 19] No such device error: Indicates a missing UTOC device or a motherboard without CAN bridge firmware flashed.

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  4. mcu 'mcu': Unable to open CAN port: Failed to transmit: [Errno 100] Network is down error: Indicates that the CAN network is not properly configured or the CAN0 interface is not started.

  5. mcu 'mcu': Unable to open CAN port: Failed to transmit: [Errno 105] Network is down error: Indicates that the CAN network buffer is too small and needs to be increased.

For detailed configuration methods for [Errno 105] Network is down and [Errno 100] Network is down errors, please refer to the CAN Configuration Document.

mcu 'mcu': Invalid CAN uuid​

Error Message: CAN UUID is invalid or cannot be recognized.

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Error Cause: The CAN ID was not entered correctly or was entered incorrectly, causing Klipper to be unable to recognize the CAN device.

Solutions: Re-search for the CAN device ID and fill it in correctly in the printer.cfg configuration file.

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

Error Message: The 'serial' option must be specified in the mcu configuration section.

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Error Cause: The USB device ID was not entered correctly or was entered incorrectly, causing Klipper to be unable to recognize the motherboard connected via USB.

Solutions: Re-search for the USB device ID and fill it in correctly in the mcu section of the printer.cfg configuration file.

Configuration Conflict Issues​

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

Error Message: Safe Z homing conflicts with homing override configuration.

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Error Cause: Both [safe_z_home] and [homing_override] function modules are configured, causing a conflict in the homing logic.

Solutions: Configure only one of these function modules and delete the other configuration. Choose to keep either [safe_z_home] or [homing_override] based on actual needs.

Temperature Detection Issues​

Error 'XXX mcu' shutdown: ADC out of range…​

Error Message: ADC (Analog-to-Digital Converter) is out of range, temperature detection is abnormal.

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Error Cause: Klipper detects a temperature exceeding the set minimum or maximum threshold, usually caused by a thermistor open circuit, short circuit, or wiring error. The system enters shutdown protection mode for safety.

Solutions: First, search for min_temp: in the configuration file and change the minimum temperature to -235, then search for max_temp: and change the maximum temperature to 500, temporarily relaxing the temperature limits for diagnostics. Next, check whether the thermistor model is correct, whether the thermistor pin configuration is correct, and whether the thermistor has a short circuit. After identifying and resolving the issue, be sure to change the temperature limits back to the original safe values.

Performance and Timeout Issues​

MCU 'mcu' shutdown: Timer too close​

Error Message: The MCU timer is too close, causing a system timeout.

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Error Cause: The main reason is that the MCU (microcontroller) processing is overloaded or the host computer (main controller) response is timed out, causing the timer interval to be too small to process tasks normally.

Solutions: First, try to reduce the stepper motor microstep setting to decrease the processing burden of each step pulse. Second, reduce the printing speed to lighten the overall system load. If the problem persists, consider re-flashing the host computer system and re-flashing the firmware.

For Raspberry Pi users, you can also use the following method to check and disable the NTP time synchronization service, reducing interference from system time synchronization:

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

The above commands first check the NTP service status, then disable the NTP synchronization feature.

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