laravel 5.4 Passport show "encryption key error : You must set the encryption key going forward to improve the security of this library"

laravel passport 安裝設定完後,若使用上出現下面錯誤 You must set the encryption key going forward to improve the security of this library - see this page for more information https://oauth2.thephpleague.com/v5-security-improvements/ 解決方法 http://www.imc4.com/archives/5.html 更新 /vendor/laravel/passport/src/PassportServiceProvider.php 中的makeAuthorizationS