Timeout with MCU / Lost communication with MCU

Timeout with MCU / Lost communication with MCU


This error occurs when the Klipper Host receives no response for its “heart beat” request or other commands for several seconds.
This error often appears in conjunction with the Got EOF when reading from device errors


  • Unreliable connection between the printer-board and the MCU
  • Inadequate / over-loaded power supply of either the host or the main power supply
  • Loose connectors / crimping connections or damaged cables
  • Incorrectly powering the printer board over USB instead of the main power supply or supplying power simultaneously via USB and main power supply
  • Issues with the USB port on the Host SBC
  • Other USB devices, e.g. webcams, hogging the USB communication

Potential solutions

  • Check the hardware / cables / connectors. Any cable in the entire printer could cause a short-circuit that potentially lets the MCU crash
  • Make sure to use a properly dimensioned, good quality power supply unit for both the host and as main power supply
  • When printing very hot (extruder and or bed) the required current can overload the power supply. Reduce the temperature, if then the error is gone, the used power supply is too weak
  • Make sure a proper USB cable is used
  • Make sure the USB connector (especially on the printer-board side) is properly having contact
  • Change the used USB port, e.g. try USB2 vs. USB3 etc
  • Remove other USB devices