When you enter the mobile phone-file management-find the installation file-open it, there will be software installation without a visa (this is a hint of wrong security certificate, and the root cause is that the software has not been successfully signed).
Solution 1: Adjust the mobile phone time:
Adjust the mobile phone system time forward for more than 3 months, and adjust the system time to the validity period of the software certificate (3 months is a cycle by default).
If the installation still prompts that the certificate has expired, continue to adjust it until it can be installed. After installation, adjust the phone time to normal time.
Solution 2: Turn off certificate checking:
Go to Settings-Program Management-Installation Settings, set online certificate checking to off, and set the default URL to none.
Then go to mobile phone-file management-click install file to install.
Solution 3: Using signature software:
Install a mobile phone signature software to sign. At present, only the SIS editor can be signed and downloaded to the mobile phone for installation (the previous free signature cannot be signed due to the closure of the certification authority and the official certificate website, but the SIS editor itself has been signed).
Install the SIS editor on the mobile phone, open it, and click the software signature.
Select an installation file, and SIS Editor will automatically load the information of the installation file.
Click Options-Signature-Software Signature.
Select Self-Signature (30 years) and click OK.
Prompt file has been changed. Do you want to keep it? Select Yes, and then you can install it.
Solution 4: Install cracking software:
If you don't want to carry out the above cumbersome solutions, you can crack the mobile phone once and for all. Go to Saipan's website to download C503 cracking software Northonsymbianhack _ Coderus _ Carson and RomPatcherPlus _ 3.1_ liteversion.sisx, install Northonsymbianhack _ Coderus _ Carson on your mobile phone, and find the north icon in the menu.
Open it and click Options-Antivirus-Quarantine List.
Click-Options-Restore All.
The choice is yes.
Exit the software, go to Settings-Program Management-Installed Programs, and find a program named Symantec Symbian Hack. Press and hold to open the uninstall menu and select uninstall it.
Install RomPatcherPlus _ 3.1_ liteversion.sisx on your mobile phone, and go to the mobile phone menu to find the ROM or system cracking icon.
Open it and check the visa-free patch and permission patch respectively.
Click Options-Set visa-free patches and permission patches to start automatically, and click Exit to exit the settings.