This is the application developer account audit time has expired or the application has been updated. When the mobile phone runs some software, it needs signature verification. If the software is not signed, it cannot run on the system. If the application signature expires, you can directly obtain the developer's account at this time, and you can reuse it after authentication. However, for most friends, it is not easy to re-certify. You can sign contracts through other channels, and you can directly choose a relatively stable signing platform. It is best to sign contracts continuously, so that you can sign contracts repeatedly.