There are three health codes: green, yellow and red. Each color has a different meaning. Users need a green code to facilitate travel. Some friends' health codes are black. What's going on here?
There may be the following reasons for the phenomenon that the health code is black: First, the health code applied by the user is under review, and the green code, yellow code or red code can be displayed after the review is completed; Second, the image has not been refreshed, click the refresh button to try; Third, the user has not been successfully authenticated. Please try again.
It is also possible that the device is unresponsive due to network delay, so you can try refreshing it again. Another situation is that there is no location service. In this case, the health code may also be displayed in black.