If the certificate expires, you can try to move the date forward on your phone, half a year or more, and then try to install it again. The validity of the certificate cannot be checked online. In Tools-Program Management-Settings-Software Installation, select All and select Off for online certificate checking.

The problem with the certificate is the relevant permissions of the mobile phone. Without a certificate signature, some software is simply not trusted, prompts that the certificate is incorrect, expired, or some file is damaged, and cannot be installed. The certificate is for some untrusted software, that is, the machine does not trust it and cannot be installed normally. The signature is used with a signing tool to generate a software signed by yourself. It is a little different from the original software before. Of course, it doesn’t mean that you can’t install software on your phone without a certificate. Some common ones can be installed directly, and those are listed as trusted software, such as qq, ucweb, etc.

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