if you need set multiDex,you can read this. Perhaps you can search some suggestion about this issue. But,android 4.4.4 will crash. Important!!!! Don't write the codes in your activity. sign: app/build.grandle multiDexEnabled true

compile "com.android.support:multidex:1.0.0"

AND change your MainApplication extends MultiDexApplication

import android.support.multidex.MultiDexApplication;//add public class MainApplication extends MultiDexApplication implements ReactApplication { //changed } I was used two days to resolve this issue. Because,search's answers is so bad........so I write it...