Now the epidemic situation is widespread, and networking is difficult. You can try it several times.
Health code is based on real data, which is declared online by citizens or people who have returned to work, and can be generated into personal QR code after background audit. Usually, it is a green code. When the verification fails, it is mostly because the personal information is accidentally filled in incorrectly, which leads to failure to display or discoloration of the health code. Then you have to modify your information. Secondly, it is also possible that your mobile phone does not have a mobile data network and no Internet access.