It probably means that your installation package has not passed verification. The following quotes other people’s answers: You may want to ask what is the use of the certificate? Certificates are used to sign software. Without a certificate, software cannot be signed. So what is the use of software signing? First of all, we need to understand the role of signatures. The third version of S60 has made major improvements in security and has stricter regulations on third-party software installed and run in the system. Certain operations related to mobile phone software and hardware security/personal information security and other aspects have been specially restricted (for example, automatic startup when the phone is turned on is one of the restricted functions). Applications must obtain a "signature" to implement these "specially restricted" functions. In other words, someone must be responsible for the safety of this operation! Programs without any signature cannot be installed and run. Signature (sign): It is to write specific tag information in specific fields of the application, indicating that the software has passed the review of the signer. The signer is responsible for the security of this software. There are roughly three types of signatures: 1. Symbian signature. That is the official signature of Symbian mobile operating system. Only software that has passed the Symbian security certification will be signed by Symbian. This type of software has the highest security level. It can be installed/run normally on the mobile phone and can realize all the functions provided by the software. Obtaining the Symbian signature requires the software author to deal directly with the Symbian official. Due to various reasons, not all software authors are able to obtain this certification. 2. Author's signature. Software authors sign the software when they release it. This type of software can be installed and run on your mobile phone (you may encounter a security warning, which can be skipped). However, those "specially restricted" functions cannot be implemented. If a piece of software does not involve such functions at all, then the software author may just sign it himself. Another possibility is that although some functions of the software fall within the scope of "specially restricted", they are not the main functions. The software author may also release an "author-signed version", which can use most functions normally, but will lose some specific functions. For example, the "Laitengtong" software has such a version, almost all functions can be used, but it cannot start automatically when the computer is turned on. 3. User signature. (This is the one currently used in the certificate area. At least read this paragraph.) Strictly speaking, this should be a "developer signature". Because Symbian provides a "development certificate" for software developers, the original intention was to allow software developers to conduct software testing. This "development certificate" is linked to the IMEI code of the machine used for testing. Software signed with this certificate can only be used on the machine corresponding to the IMEI code and cannot be used on other machines. What we call "self-signing" actually makes use of this method. To put it bluntly, you say you are developing software, you provide the IMEI code of your test machine, and Symbian issues you a "development certificate". You use this certificate to sign your "test software". You are solely responsible for your own "development behavior"! That's all. In addition, the development certificate is valid for six months from the date of issuance. However, there is no limit on the use time of programs signed within the validity period of the certificate. If you want to use signatures, you can go to the Saipan forum to apply for a new certificate and signing tool.