Error: Could not find or load main class worker.org.gradle.process.internal.worker.GradleWorkerMain after installing Firebase in Flutter project

Question

I am encountering an error when trying to build my Flutter project after integrating Firebase into it. Initially, I was trying to install Firebase dependencies (including firebase_core and firebase_auth), but since then, I’ve run into several Gradle-related issues during the build process.

The specific error I'm getting is:

Error: Could not find or load main class worker.org.gradle.process.internal.worker.GradleWorkerMain
Caused by: java.lang.ClassNotFoundException: worker.org.gradle.process.internal.worker.GradleWorkerMain

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':gradle:compileGroovy'.
> Failed to run Gradle Worker Daemon
   > Process 'Gradle Worker Daemon 4' finished with non-zero exit value 1

Here’s what I’ve done so far to troubleshoot:

Cleared Gradle caches multiple times using rm -rf ~/.gradle/caches/

Rebuilt the Gradle wrapper with ./gradlew wrapper --gradle-version 8.3 --distribution-type all.

Set Java version to 17 (as Firebase and Android Gradle Plugin require it).

Ensured that com.android.tools.build:gradle version is compatible with Gradle 8.x.

Deleted the .gradle and .idea folders to avoid any potential IDE cache issues.

Tried building the project via Android Studio and using command line ./gradlew clean followed by ./gradlew assembleDebug.

I’m using Gradle 8.3 and Java 17, and the issue persists.

After these steps, I am still facing the same issue. This error appeared after trying to add Firebase to the project, and I suspect that the Firebase installation might have triggered a conflict with my Gradle setup.

Below is my settings.gradle:

pluginManagement {
    def flutterSdkPath = {
        def properties = new Properties()
        file("local.properties").withInputStream { properties.load(it) }
        def flutterSdkPath = properties.getProperty("flutter.sdk")
        assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
        return flutterSdkPath
    }()

    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")

    repositories {
        google()
        mavenCentral()
        gradlePluginPortal()
    }
}

plugins {
    id "dev.flutter.flutter-plugin-loader" version "1.0.0"
    id "com.android.application" version "8.1.0" apply false
    // START: FlutterFire Configuration
    id "com.google.gms.google-services" version "4.3.15" apply false
    // END: FlutterFire Configuration
    id "org.jetbrains.kotlin.android" version "1.8.22" apply false
}

include ":app"

And below is the build.gradle:

plugins {
    id "com.android.application"
    // START: FlutterFire Configuration
    id 'com.google.gms.google-services'
    // END: FlutterFire Configuration
    id "kotlin-android"
    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
    id "dev.flutter.flutter-gradle-plugin"
}

android {
    namespace = "com.example.ticketmasterapp"
    compileSdk = flutter.compileSdkVersion
    ndkVersion = flutter.ndkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_11
        targetCompatibility JavaVersion.VERSION_11
    }

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_11
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId = "com.example.ticketmasterapp"
        // You can update the following values to match your application needs.
        // For more information, see: https://flutter.dev/to/review-gradle-config.
        minSdk = flutter.minSdkVersion
        targetSdk = flutter.targetSdkVersion
        versionCode = flutter.versionCode
        versionName = flutter.versionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig = signingConfigs.debug
        }
    }
}

flutter {
    source = "../.."
}

Has anyone encountered this issue when integrating Firebase with Flutter? What else can I try to resolve the error?

Please try this one, open terminal, execute these commands: cd android and then ./gradlew build --stacktrace --info — DevQt, Commented Nov 23, 2024 at 8:22
Let's see if the provided error on the first attempt stays the same. — DevQt, Commented Nov 23, 2024 at 8:23
I already updated my answer just now. You can do it, I know you can. — DevQt, Commented Nov 23, 2024 at 21:52

DevQt · Accepted Answer · 2024-11-25 00:56:58Z

After installing firebase_core and firebase_auth,

I didn't reproduce the exception like yours. This means that it works fine with my setup.

Before anything else, these are some prerequisites and build setups to consider:

flutter doctor -v output:

[√] Flutter (Channel stable, 3.24.5, on Microsoft Windows [Version 10.0.26100.2454], locale en-US)
    • Flutter version 3.24.5 on channel stable at C:\Users\alagu\FlutterSDK\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision dec2ee5c1f (10 days ago), 2024-11-13 11:13:06 -0800
    • Engine revision a18df97ca5
    • Dart version 3.5.4
    • DevTools version 2.37.3

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at C:\Users\alagu\AppData\Local\Android\Sdk
    • Platform android-35, build-tools 35.0.0
    • ANDROID_SDK_ROOT = C:\Users\alagu\AppData\Local\Android\Sdk
    • Java binary at: C:\Program Files\Java\jdk-17\bin\java
    • Java version Java(TM) SE Runtime Environment (build 17.0.12+8-LTS-286)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Enterprise 2022 17.10.2)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Enterprise
    • Visual Studio Enterprise 2022 version 17.10.35004.147
    • Windows 10 SDK version 10.0.22621.0

[√] Android Studio (version 2022.3)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.11+0--11852314)

[√] Android Studio (version 2024.1)
    • Android Studio at C:\Program Files\Android\Android Studio1
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.10+0--11609105)

[√] VS Code (version 1.95.3)
    • VS Code at C:\Users\alagu\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.100.0

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.26100.2454]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 131.0.6778.86
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 131.0.2903.63

[√] Network resources
    • All expected network resources are available.

• No issues found!

Please notice that I'm using Java 17, and I am using Android Studio for some Flutter development setup purposes.

So make sure that you are utilizing Java 17 and have it verified with proper configuration in the system variables.

settings.gradle file:

pluginManagement {
    def flutterSdkPath = {
        def properties = new Properties()
        file("local.properties").withInputStream { properties.load(it) }
        def flutterSdkPath = properties.getProperty("flutter.sdk")
        assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
        return flutterSdkPath
    }()

    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")

    repositories {
        google()
        mavenCentral()
        gradlePluginPortal()
    }
}

plugins {
    id "dev.flutter.flutter-plugin-loader" version "1.0.0"
    id "com.android.application" version "8.1.4" apply false
    id "org.jetbrains.kotlin.android" version "2.0.21" apply false
}

include ":app"

gradle-wrapper.properties file:

distributionUrl=https\://services.gradle.org/distributions/gradle-8.3-all.zip

app\build.gradle file:

plugins {
    id "com.android.application"
    id "kotlin-android"
    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
    id "dev.flutter.flutter-gradle-plugin"
}

android {
    namespace = "com.example.flutter_build_ref3"
    compileSdk = flutter.compileSdkVersion
    ndkVersion = flutter.ndkVersion

    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId = "com.example.flutter_build_ref3"
        // You can update the following values to match your application needs.
        // For more information, see: https://flutter.dev/to/review-gradle-config.
        minSdk = 23 //flutter.minSdkVersion
        targetSdk = flutter.targetSdkVersion
        versionCode = flutter.versionCode
        versionName = flutter.versionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig = signingConfigs.debug
        }
    }
}

flutter {
    source = "../.."
}

The provided configuration setup is only applicable to my environment setup, so you don't have to copy it unless we have the same environment setup (i.e., based on the generated information from flutter doctor -v)

Since you have an exception,

Error: Could not find or load main class worker.org.gradle.process.internal.worker.GradleWorkerMain Caused by: java.lang.ClassNotFoundException: worker.org.gradle.process.internal.worker.GradleWorkerMain

FAILURE: Build failed with an exception.

* What went wrong: Execution failed for task ':gradle:compileGroovy'.
> Failed to run Gradle Worker Daemon
   > Process 'Gradle Worker Daemon 4' finished with non-zero exit value 1

So, there's a conflict in compiling the core components of your build.

Again, be sure that you properly add the Java 17 SDK or Java 11 SDK path installation in the JAVA_HOME and PATH under the system variables.

After you configure your Environment Variables > system variables. A Windows restart is a best practice to make sure that the JDK is integrated properly within your machine (just to make sure XD).

Then repeat the usual steps, perform flutter clean, then flutter pub get.

Then, build your app again.

Update:

Don't be confused about wondering why your Flutter app worked well before but suddenly introduced a build exception after installing a certain plugin. You have to take note that other versions of Java JDK might maintain compatibility with your previous build. But, unfortunately, some particular plugins or dependencies triggered the compatibility issues, so the conciseness of the Java JDK should be provided, or else your build won't be executed properly.

Clarifications:

Please make sure that you didn't manually add the firebase_core and firebase_auth plugins directly to the pubspec.yaml, unless you know what you're doing. I suggest adding it by flutter pub add firebase_core and flutter pub add firebase_auth because your IDE will determine which version is compatible with your environment and development setup.

If there's some other newly introduced exception, and you are continually configuring your development setup.

Please consider the following debugging approaches:

PS C:\PATH_TO_YOUR_PROJECT\android> ./gradlew build --stacktrace --info

For logging optimizations where you only get what you need, please read Logging

To get the complete information about your building process.

UPDATE 2.0:

I just want to make things clear; you need to do this if you suspect that your Flutter project config messed up UNINTENTIONALLY

Here's what I performed:

Since the conflict you encountered is related to the java.lang.ClassNotFoundException and Gradle. But to mention my previous case, I verified the root cause by myself by initially setting up a certain environment setup (e.g., Java 17 [since it works for me]) and then I created a new Flutter application.

I reviewed the configuration files and compared them to my actual Flutter project, so I was able to cross-check where the improper configurations were.

(in my newly created Flutter application) Then I add the plugin through these commands in the terminal:

flutter clean

NOTE: This is optional, sometimes I do this when I feel it's necessary, but since the issue is related to the Gradle build, it is better to clear up its caches to prevent further conflicts.

flutter pub get

flutter pub add <plugin_name>

NOTE: A certain plugin that I am using which also introduced an exception with my actual project.

flutter pub get

Then, I will build the app based on requirements (i.e., whether I need to build for Android or web).

or sometimes, I go to the Android directory within my project just to run a platform-specific command for Android:

PS C:\path_to_your_project\android> ./gradlew build --stacktrace --info

To relate to your case, you need to adjust your side for the plugin you used to become compatible, of course, based on the suggestions of the exception of the log if there's one.

If it is about java.lang.ClassNotFoundException, migrate to Java 17 and perform gradle-specific and platform-specific (i.e., Android) clear caching, but sometimes flutter clean will do. Since you already know what are the proper configurations based on your environment setup, repeating the UPDATE 2.0 will become optional.

Also, note that this is considered as one of the last resorts if you get confused with your project setup. Please don't get me wrong, I didn't mean to say that you're confused, but instead to give you an insight in order to overcome your case issue.

Reading the plugin's changelog is a good practice as well, btw.

PS: Sorry for being too verbose here, I need to do this to express my knowledge and understanding about the troubleshooting of your case.

I hope it helps! ❤️

Have you tried to check your java installed by executing this command java --version? — DevQt, Commented Nov 23, 2024 at 9:30

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