The health code can't be opened until it has been updated for several days. You have to click a prompt in the lower left corner, re-authenticate, enter your temperature at that time, then click the agreement, continue to click OK, and the health code will come out.
Other reasons may be that the network is not good or the mobile phone is broken. If it is caused by bad network, it is recommended to replace the network. If the phone breaks down, it is recommended to restart the phone. Another possibility is that there is a bug in the software itself and the system crashes, so we have to wait for the staff to restore the system.