error Failed to install the app. Make sure you have the Android development environment set up: https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment. Run CLI with --verbose flag for more details. Error: Command failed: gradlew.bat app:installDebug -PreactNativeDevServerPort=8081 FAILURE: Build failed with an exception.
You have to clean cache:
Step 1: Open terminal and go to Android folder:
Step 2: go back working folder then start app: