first you add .(dot)operator to you env file because when you start you project first time env file don't start with .(dot)operator so set .env after that un comment CI_ENVIRONMENT and make it CI_ENVIRONMENT = development now you see your application in development mode. But problem is you can't see CodeIgniter fire icon in CodeIgniter built-in server php spark serve (localhost:8080) but you see fire icon in Apache server on you application (localhost/your_project_name/public).