An expired application signature means that the application developer account review 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.

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Benefits of applying signatures:

1, application upgrade. If you want to upgrade the version of the application, you must sign it with the same certificate, because the system will only allow you to install and upgrade this application if you sign it with the same certificate. If the user signs with a different certificate, the system will ask the application to change its name, which is equivalent to installing a new application.

2. If different applications want to share data or code, they should run in the same process and sign with the same certificate. Sign multiple applications with the same certificate, and use the permission check based on signature to enjoy the code and data between applications in a safe way.