App crashes by initialization of ReactNativeHostWrapper: ClassNotFoundException: expo.modules.ExpoModulesPackageList

[jmurga97]

App crashes with ClassNotFoundException: expo.modules.ExpoModulesPackageList when integrating Expo bare-minimum template with native Android app

Description

I've been trying for several days to create a simple integration demo between a native Android application and an Expo CLI app created with the bare-minimum template.

I've successfully created the AAR package and included it as a local dependency in my native application. The native app builds successfully, but crashes on startup with an error originating from ReactNativeHostManager initialization.

Error

2025-09-04 13:12:56.079  5655-5655  ExpoModulesPackage      com.example.bkt_fe_native_coex_poc   E  Couldn't get expo package list. (Ask Gemini)
                                                                                                    java.lang.ClassNotFoundException: expo.modules.ExpoModulesPackageList
                                                                                                    	at java.lang.Class.classForName(Native Method)
                                                                                                    	at java.lang.Class.forName(Class.java:597)
                                                                                                    	at java.lang.Class.forName(Class.java:502)
                                                                                                    	at expo.modules.ExpoModulesPackage.packageList_delegate$lambda$1(ExpoModulesPackage.kt:23)
                                                                                                    	at expo.modules.ExpoModulesPackage.$r8$lambda$QFBV9-FY5jLEWS4oBZ76Yb8QIkI(Unknown Source:0)
                                                                                                    	at expo.modules.ExpoModulesPackage$$ExternalSyntheticLambda0.invoke(D8$$SyntheticClass:0)
                                                                                                    	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
                                                                                                    	at expo.modules.ExpoModulesPackage$Companion.getPackageList(ExpoModulesPackage.kt:21)
                                                                                                    	at expo.modules.ApplicationLifecycleDispatcher.getCachedListeners(ApplicationLifecycleDispatcher.kt:13)
                                                                                                    	at expo.modules.ApplicationLifecycleDispatcher.onApplicationCreate(ApplicationLifecycleDispatcher.kt:20)
                                                                                                    	at com.bmb.demorn.ReactNativeHostManager.initialize(ReactNativeHostManager.kt:154)
                                                                                                    	at com.example.bkt_fe_native_coex_poc.MainActivity.onCreate(MainActivity.kt:21)

Code

Native MainActivity

import com.bmb.demorn.ReactNativeHostManager

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        //ReactNativeHostManager.initialize(this.application)
        ReactNativeHostManager.shared.initialize(this.application)
        // improved conf Edge-to-Edge
        enableEdgeToEdge()
        WindowCompat.setDecorFitsSystemWindows(window, false)

        setContent {
            BktfenativecoexpocTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    BaseScreenLayout(
                        title = "Demo",
                    ) {
                        HomeScreen()
                    }
                }
            }
        }
    }
}

ReactNativeHostManager

class ReactNativeHostManager {
    companion object {
        val shared: ReactNativeHostManager by lazy { ReactNativeHostManager() }
        private var reactNativeHost: ReactNativeHost? = null
        private var reactHost: ReactHost? = null
    }

    fun getReactNativeHost(): ReactNativeHost? {
        return reactNativeHost
    }

    fun getReactHost(): ReactHost? {
        return reactHost
    }

    fun initialize(application: Application) {
        if (reactNativeHost != null && reactHost != null) {
            return
        }

        SoLoader.init(application, OpenSourceMergedSoMapping)
        if (BuildConfig.IS_NEW_ARCHITECTURE_ENABLED) {
            load()
        }
        ApplicationLifecycleDispatcher.onApplicationCreate(application)

        val jsMainModuleName = ".expo/.virtual-metro-entry"

        val reactApp = object : ReactApplication {
            override val reactNativeHost: ReactNativeHost = ReactNativeHostWrapper(application,
                object : DefaultReactNativeHost(application) {
                    override fun getPackages(): MutableList<ReactPackage> {
                        return PackageList(application).packages
                    }

                    override fun getJSMainModuleName(): String = jsMainModuleName
                    override fun getBundleAssetName(): String = "index.android.bundle"

                    override fun getUseDeveloperSupport() = BuildConfig.DEBUG

                    override val isNewArchEnabled: Boolean = BuildConfig.IS_NEW_ARCHITECTURE_ENABLED
                    override val isHermesEnabled: Boolean = BuildConfig.IS_HERMES_ENABLED
                })

            override val reactHost: ReactHost
                get() = getDefaultReactHost(application, reactNativeHost)
        }

        reactNativeHost = reactApp.reactNativeHost
        reactHost = reactApp.reactHost

    }
}

Library build.gradle.kts

import groovy.json.JsonOutput
import groovy.json.JsonSlurper
import org.gradle.jvm.toolchain.JavaLanguageVersion

plugins {
    id("com.android.library")
    id("org.jetbrains.kotlin.android")
    id("com.facebook.react")
    id("com.callstack.react.brownfield")
    `maven-publish`
}

reactBrownfield {
    /**
     * This will be available from `com.callstack.react.brownfield` version > 3.0.0
     * It takes care of linking expo dependencies like expo-image with your AAR module.
     */
    isExpo = true
}

react {
    autolinkLibrariesWithApp()
}

android {
    namespace = "com.bmb.demorn"
    compileSdk = 35

    defaultConfig {
        minSdk = 24

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
        consumerProguardFiles("consumer-rules.pro")
        
        buildConfigField("boolean", "IS_NEW_ARCHITECTURE_ENABLED", properties["newArchEnabled"].toString())
        buildConfigField("boolean", "IS_HERMES_ENABLED", properties["hermesEnabled"].toString())
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
    }
    kotlinOptions {
        jvmTarget = "17"
    }
}

dependencies {
    
    api("com.facebook.react:react-android:0.79.6")
    api("com.facebook.react:hermes-android:0.79.6")

    implementation("androidx.core:core-ktx:1.17.0")
    implementation("androidx.appcompat:appcompat:1.7.1")
    implementation("com.google.android.material:material:1.12.0")
    testImplementation("junit:junit:4.13.2")
    androidTestImplementation("androidx.test.ext:junit:1.3.0")
    androidTestImplementation("androidx.test.espresso:espresso-core:3.7.0")

}

// ... rest of the build configuration

Build Script

set -e

trap 'echo "Build interrupted"; exit 1' INT

pushd android
./gradlew clean
./gradlew demorn:bundleReleaseAar
./gradlew demorn:bundleDebugAar

echo -e "✅ AARs built successfully: \n android/react-brownfield/build/outputs/aar/react-brownfield-debug.arr \n android/react-brownfield/build/outputs/aar/react-brownfield-release.arr"

 ./gradlew publishToMavenLocal

echo "✅ AARs published to mavenLocal: com.callstack.react:react-brownfield"

Additional Information

• I followed the guide at https://www.rockjs.dev/docs/brownfield/android strictly and manually (npm create rock gives me errors when generating the AAR package)
• I had to add the following modifications to build.gradle.kts, otherwise the AAR package wouldn't be generated:

afterEvaluate {
    tasks.named("releaseSourcesJar") {
        dependsOn("copyAutolinkingSources")
        dependsOn("generateCodegenArtifactsFromSchema")
    }
    
    // Handle debug sources jar if it exists
    tasks.findByName("debugSourcesJar")?.let { task ->
        task.dependsOn("copyAutolinkingSources")
        task.dependsOn("generateCodegenArtifactsFromSchema")
    }
}

Environment

• React Native: 0.79.6
• Expo CLI with bare-minimum template
• Android compileSdk: 36
• minSdk: 24
• Kotlin
• New Architecture: Enabled

The error seems to be related to missing expo.modules.ExpoModulesPackageList class during initialization. Any guidance on how to resolve this would be greatly appreciated.

[VigneshPandianB25]

@jmurga97 please add your bundle file in android and ios side,