There are two main reasons why the health code can't work normally: your mobile phone network signal is too poor, so you can switch the environment first and try again or change the mobile network. After changing the network, you need to reopen the health code and refresh it three times. It is also possible that the health code crashed in the background, so just quit and log in again or log in later.
The health code system has formed a set of standards. Most of the operating companies of health code and nucleic acid detection systems are built through bidding in local big data centers, and technology providers can also see it from shareholders. Local health codes can be selected according to the needs of different regions and the needs of epidemic prevention and control in various places.