Run Button Grayed out: Android Studio
You should initially configure the application.
- Click the edit configuration in the combo box left to run button then:
- Select the app module
After an update of Android Studio or major changes to your project structure, you need to restart Android Studio and for the first time press run from the dropdown menu
If you've made major changes to your project structure, it sometimes takes restarting Android Studio to regain the ability to Run your project. Worked for me.