The health code has no color, which may be a system problem. I suggest you restart to find it, or restart it after turning it off, so that the color of the health code can basically come out. Health codes are based on actual data and can be generated by citizens or people who have returned to work through online declaration and background audit. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city. The introduction of the health code aims to make the work of returning to work more accurate, scientific and orderly.