composer require maxsky/lumen-app-key-generatorSupport generate APP_KEY in Lumen same as Laravel.
Modify $commands variable in app/Console/Kernel:
protected $commands = [
\Illuminate\Console\KeyGenerateCommand::class,
];Then run command at project root path:
php artisan key:generate
php artisan key:generate --showAdd param --show will display a generate key without replace APP_KEY in .env file.