Execute under the project root directory:
php artisan key:generate
But in fact, the above error may still be reported after the .envinternal already exists APP_KEYor the above statement is created.
Similarly, execute in the project root directory:
php artisan serve
After refreshing, you can log in.
The reason is that the project uses the built-in php web server to drive the website, and the above command starts the server, and it can be accessed normally