Why React-Native Couldn't start project on Android connection with Expo?

Question

Couldn't start project on Android.

Error : No Android connected device found, and no emulators could be started automatically.

Please connect a device or create an emulator (https://docs.expo.io/workflow/android-studio-emulator).

Then follow the instructions here to enable USB debugging:

https://developer.android.com/studio/run/device.html#developer-device-options. If you are using Genymotion go to Settings -> ADB, select "Use custom Android SDK tools", and point it at your Android SDK directory.

Answer 1

In order to run your React Native application, you first need to run an emulator seperately. It won't start an emulator automatically like a native Android Studio build.

• Create an AVD using this tutorial.

• Note down your AVD name, if you are gonna run it without Android Studio.

• Run below code in a Command Prompt window to start emulator without Android Studio. Assuming that you have installed your SDK in default location, otherwise change it to your location.

  cd C:\Users\%USERNAME%\AppData\Local\Android\Sdk\emulator
  emulator -avd Pixel_2_API_30
  

• Pixel_2_API_30 is the name of AVD so change it to yours.

For Mac (Followed this article)

Assuming your Android SDK was installed to the default location…

• Export the emulator to your PATH.

  echo 'export PATH=$PATH:~/Library/Android/sdk/emulator/' >> ~/.bash_profile

• Reload your terminal from source.

  source ~/.bash_profile

• Now you can show all the emulators you’ve already created.

  emulator -list-avds

• You can run any of them by typing emulator and then @. So if one of your devices is called 'MyPixelDevice', you’ll run it like so

  emulator @MyPixelDevice

Once your emulator is running then you can run your React Native build as stated in this setup guide.