## Troubleshooting

1\. After uploading the code, micro:bit on-board dot matrix shows a crying face and then scrolls to display the error messages.

2\. If you upload the code of Mciro:bit basic projects, please click ![Img](./media/5457.png) to check whether any characters or signs are accidentally added or deleted. Yet some warnings may show up after checking, which are not errors.

3\. If you upload the code of the smart car projects, please check whether the micro:bit library is imported. For how, please refer to “**Import Library to Mciro:bit on MU**”.

4\. After uploading the code, there is no message on the serial monitor after you click ![Img](./media/5530.png). Please remember to press the on-board reset button at the back of Micro:bit, as shown below:

![Img](./media/455.png)