- the serial port not connected. To use USB connect the Robot, select corresponding COM port under “Connect -> Serial Port “;
- Serial port has been used by other device. The Robot is connected by 2.4G or Bluetooth, check it is disconnected and remove it from the Robot.
- run mBlock under Administrator authorization. In some situation, the software need run some Arduino function which need Administrator permission. Run the software with Administrator permission would solove this situation.