NativeModules crashing in Release Builds

The app runs perfectly fine in debug mode on Android. However, when I attempt to build a release version the app crashes whenever it attempts to call into the native module.

Environment

nvironment: OS: macOS High Sierra 10.13.3 Node: 9.5.0 Yarn: 1.3.2 npm: 5.6.0 Watchman: 4.9.0 Xcode: Xcode 9.2 Build version 9C40b Android Studio: 3.0 AI-171.4443003

Packages: (wanted => installed) react: 16.2.0 => 16.2.0 react-native: 0.54.0 => 0.54.0

Expected Behavior

Native Module should be available inside of the JavaScript and not crash.

Actual Behavior

App crashes. com.facebook.react.common.JavascriptException: undefined is not an object (evaluating 'c.NativeModules.ActivityModule.finishActivity'), stack:

Steps to Reproduce

ActivityModule.kt

internal class ActivityModule(reactContext: ReactApplicationContext): ReactContextBaseJavaModule(reactContext) {
  override fun getName(): String {
    return "ActivityModule"
  }

  @ReactMethod
  fun finishActivity() {
    reactApplicationContext?.currentActivity?.finish()
  }
}

MyReactPackage.kt

internal class MyReactPackage: ReactPackage {
  override fun createNativeModules(reactContext: ReactApplicationContext): List<NativeModule> {
    return listOf(
      ActivityModule(reactContext),
      DimensionsModule(reactContext)
    )
  }

  override fun createViewManagers(reactContext: ReactApplicationContext?): MutableList<com.facebook.react.uimanager.ViewManager<View, ReactShadowNode<*>>> {
    return Collections.emptyList()
  }
}

MainApplication.java

@Override
protected List<ReactPackage> getPackages() {
  return Arrays.<ReactPackage>asList(
    new MyReactPackage(),
    new MainReactPackage()
  );
}

fake-navigation.js

const finish = () => {
  NativeModules.ActivityModule.finishActivity();
};

Calling the finish() function above crashes the app

E/ReactNativeJS: undefined is not an object (evaluating 'c.NativeModules.ActivityModule.finishActivity')
E/AndroidRuntime: FATAL EXCEPTION: mqt_native_modules
        Process: com.myapp.app, PID: 15496
        com.facebook.react.common.JavascriptException: undefined is not an object (evaluating 'c.NativeModules.ActivityModule.finishActivity')

[mdvacca]

@scottschmitz Do you have proguard enabled? If so, can you try to disabling proguard and test if this still happens in Release mode? https://facebook.github.io/react-native/docs/signed-apk-android.html

[scottschmitz]

Thanks! It was in fact a proguard issue. I didn’t realize that when I added React Native to my project that the proguard rules were not added into the folder with my other rules.