unable to load script from assets

When I execute the command react-native run-android I get the following error message:

Unable to load script. Make sure you're either running a Metro server (run 'react-native start') or that your bundle 'index.android.bundle' is packaged correctly for release.

Error message on device

I have read many solutions but they have not resolved the problem. I tried:

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

But when I execute command:

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

This appears:

Message

I want to start react-native but I have been trying to solve this error for 3 days. Please help.