My solution is change module name in "AppDelegate.m"
from moduleName:@"AwesomeProject"
to moduleName:@"YourNewProjectName"
Or
Open index.js and update
AppRegistry.registerComponent('YourProjectName', () => YourComponentName);
If it is a probem with Android then make sure following files.
In MainActivity.java file whatever you return in the getMainComponentName() it should match
@Override
protected String getMainComponentName() {
return"testapp";
}
with index.js appName
AppRegistry.registerComponent(appName, () => App);