$ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, v1.2.1, on Linux, locale en_US.UTF-8)
[!] Android toolchain - develop for Android devices (Android SDK version 28.0.3) ✗ Android license status unknown.
[✓] Android Studio (version 3.3)
[!] IntelliJ IDEA Ultimate Edition (version 2018.3)
✗ Flutter plugin not installed; this adds Flutter specific functionality. ✗ Dart plugin not installed; this adds Dart specific functionality.
[!] VS Code (version 1.31.1)
✗ Flutter extension not installed; install from https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter
[!] Connected device ! No devices available
The solution is
It worked for me!