The health code can't be displayed normally, mainly because of network problems. Please connect your mobile phone to the 4G network or WLAN, and then open the health code, so that you can travel safely. If you haven't applied for a health code, please click the "Epidemic Prevention Health Code" button on the payment page of WeChat App, then click the "View Epidemic Prevention Health Code" button, and then get your own health code according to the system prompts.