I dont't know, i try
CodePudding user response：
Type flutter doctor on your terminal and see what is the problem
CodePudding user response：
This is because your system has internet connection protected with invalid or self-signed certificate.
Easy solution - check your system time, maybe wrong date.
If not, and you are using Windows, check if your system has self-signed certificate. You can try to install valid SSL root certificates (if it has) or use parameter DART_VM_OPTIONS=--root-certs-file=<your_cert>
In Linux certs also can be outdated, fresh certificates usually in system repo, just update your system.
At last, check your internet connection - if you using some type of proxi or firewall (or antivirus with built-in firewall) you can face this error. Try to connect to internet directly or with different provider.