Question: I'm new in react-native.
I have run react native project on Ubuntu by using 'react-native run-android' command. And I got the error on emulator 
"Unable to load script from assets 'index.android.bundle'.Make sure your bundle is packaged correctly or you are running a package server."

Answer: 
This helped me resolve the problem in following steps.

* If not than (in project directory) mkdir android/app/src/main/assets
* `react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res`
* `react-native run-android`
I discovered a solution suggested in the thread at <https://github.com/facebook/react-native/issues/15388>

It is to manually set the *Debug server host & port for device* setting for the app on the phone.

**Step by Step to eject and run a CRNA on Android**

In terminal:

1. `create-react-native-app myApp`
2. `cd myApp`
3. `yarn run eject` (I used default options "regular React Native project")
4. `react-native run-android`

*(now the app should be compiled and installed on the phone)*

On phone:

5. Run the app (expect to see the red error screen! - click Dismiss button in bottom left)
6. Shake the phone and pick **Dev Settings**
7. Pick **Debug server host & port for device** and set to 192.168.x.x:8081 (make it your actual LAN IP of course)
8. Restart app on phone and you should see green bar at the top "Loading from 192.168.x.x:8081..."
9. You should also see some "Bundling `index.js`" action in the Metro Bundler (that opened when running `react-native run-android`)
10. After the bundle is finished, the app should be running on your Android device!

Live Reload (when source files change) also works - just shake the phone and touch "Enable Live Reload"

You can run the project from Android Studio, but you need to first start the Metro Bundler with the command `react-native start` in the CRNA project root.