Suitable for beginners of React Native, however, 1. Ruby on Rails is missing, so those who do not have a related stack must learn it separately and then follow the course. - You can follow the course after learning ROR installation/MVC example once 2. There was a bug in some react packages in the version I installed - Button: string syntax related errors need to be updated to the next version npm i -S react-native@0.57.1 npm add @babel/runtime npm i schedule@0.4.0 --save-dev npm i - Google dependency related In bundle.gradle, google() dependency syntax needs to be moved to the top for the final build In android config configurations.all {exclude group: 'com.android.support', module: 'support-v4'} The required configuration is complete after setting - If the rails DB schema does not pour After updating rake from where the Gemfile is, bundle install --path rake-12.3.1 , it is created normally ... The time difference of the course is a bit Maybe because of that.. It took me a bit longer to catch up on errors like version errors than the actual 11-hour class. ps. It's a paid course, so I hope you update it! Thank you.