Signature verification failed, which is a possible problem when accessing secure connections such as HTTPS. Depending on the specific App, there are two consequences, one is that it can't be done at all, and the other is to give a warning but allow it, such as continuing to open encrypted web pages. The reason for this problem is that the developer on the server side uses encryption instead of the standard, but the generation of the key certificate is not standardized, for example, the public CA certificate is not used to sign or the license period expires, or the client cannot connect to the CA server to verify the validity of the certificate because of network environment problems, for example, CA is a foreign server, and an inappropriate proxy or VPN is set, which may also lead to this problem.