javafluttergradle

New problem during fixing incompatibility between Gradle and Java versions in Flutter

I've tried the solution in this stackoverflow QnA and also followed web links: this and this. Below is a summary of what I've tried:

Steps:

  1. Checked my java version: My system had a java version 21.0.5, but this is not configured to be used as JAVA_HOME environment variable is not set. So, the default java shipped with Android studio is used which is version 21.0.4 as stated in the output of flutter doctor --verbose.

  2. Checked the Compatibality Matrix and used both Gradle versions 8.4 and 8.5 shown parallel to Java version 21 in the configuration process that follows.

  3. Opened a terminal, and went to <project_root>/android/ directory and executed the following commands:

    ./gradlew wrapper --gradle-version=8.4

This resulted in following error:

Welcome to Gradle 7.6.3!

Here are the highlights of this release:
 - Added support for Java 19.
 - Introduced `--rerun` flag for individual task rerun.
 - Improved dependency block for test suites to be strongly typed.
 - Added a pluggable system for Java toolchains provisioning.

For more details see https://docs.gradle.org/7.6.3/release-notes.html

Starting a Gradle Daemon, 2 incompatible and 1 stopped Daemons could not be reused, use --status for details
> Task :gradle:compileGroovy FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':gradle:compileGroovy'.
> BUG! exception in phase 'semantic analysis' in source unit '/home/ajthapa/dev/tooling/flutter/packages/flutter_tools/gradle/src/main/groovy/app_plugin_loader.groovy' Unsupported class file major version 65

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 14s
1 actionable task: 1 executed

The same thing happened with version 8.5.

  1. Then I created a backup of <project_root>/android/gradle/wrapper/gradle-wrapper.properties in that directory, and changed the content of the original file from:
distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.3-all.zip

to:

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-all.zip

and then run the project which resulted in following error:

Launching lib/main.dart on sdk gphone64 x86 64 in debug mode...
Warning: This version only understands SDK XML versions up to 3 but an SDK XML file of version 4 was encountered. This can happen if you use versions of Android Studio and the command-line tools that were released at different times.
Checking the license for package Android SDK Build-Tools 30.0.3 in /home/ajthapa/Android/Sdk/licenses
License for package Android SDK Build-Tools 30.0.3 accepted.
Preparing "Install Android SDK Build-Tools 30.0.3 (revision: 30.0.3)".
"Install Android SDK Build-Tools 30.0.3 (revision: 30.0.3)" ready.
Installing Android SDK Build-Tools 30.0.3 in /home/ajthapa/Android/Sdk/build-tools/30.0.3
"Install Android SDK Build-Tools 30.0.3 (revision: 30.0.3)" complete.
"Install Android SDK Build-Tools 30.0.3 (revision: 30.0.3)" finished.
warning: [options] source value 8 is obsolete and will be removed in a future release
warning: [options] target value 8 is obsolete and will be removed in a future release
warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.

(Above warnings also arose with new projects, but the projects run. The following may be of our current concern:)

3 warnings
ERROR:/home/ajthapa/dev/projects/flutter/NepaliUnitConv/00__Play_Store_builds/00__Closed_Test_version/update__feature_tests/NepaliUnitConv_v1.0.29__without_Admob_Ads/nepali_unit_conv/build/path_provider_android/intermediates/runtime_library_classes_jar/debug/classes.jar: D8: java.lang.NullPointerException: Cannot invoke "String.length()" because "<parameter1>" is null

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:mergeLibDexDebug'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Failed to transform classes.jar (project :path_provider_android) to match attributes {artifactType=android-dex, asm-transformed-variant=NONE, com.android.build.api.attributes.AgpVersionAttr=7.3.0, com.android.build.api.attributes.BuildTypeAttr=debug, com.android.build.gradle.internal.attributes.VariantAttr=debug, dexing-enable-desugaring=true, dexing-enable-jacoco-instrumentation=false, dexing-is-debuggable=true, dexing-min-sdk=21, org.gradle.libraryelements=jar, org.gradle.usage=java-runtime}.
      > Execution failed for DexingWithClasspathTransform: /home/ajthapa/dev/projects/flutter/NepaliUnitConv/00__Play_Store_builds/00__Closed_Test_version/update__feature_tests/NepaliUnitConv_v1.0.29__without_Admob_Ads/nepali_unit_conv/build/path_provider_android/intermediates/runtime_library_classes_jar/debug/classes.jar.
         > Error while dexing.

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 4m 10s
Error: Gradle task assembleDebug failed with exit code 1

Exited (1).

My project ran perfectly when I had Android Studio Koala installed, and now these errors have risen when I removed Koala version and installed Ladybug.

How can I fix this?

Update 01: Output of flutter doctor --verbose :

[✓] Flutter (Channel stable, 3.27.2, on Ubuntu 24.04.1 LTS 6.8.0-51-generic, locale en_GB.UTF-8)
    • Flutter version 3.27.2 on channel stable at /home/ajthapa/dev/tooling/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 68415ad1d9 (4 days ago), 2025-01-13 10:22:03 -0800
    • Engine revision e672b006cb
    • Dart version 3.6.1
    • DevTools version 2.40.2

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.1)
    • Android SDK at /home/ajthapa/Android/Sdk
    • Platform android-35, build-tools 35.0.1
    • Java binary at: /home/ajthapa/dev/tooling/android-studio/jbr/bin/java
    • Java version OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)
    • All Android licenses accepted.

[✓] Chrome - develop for the web
    • Chrome at google-chrome

[✓] Linux toolchain - develop for Linux desktop
    • Ubuntu clang version 18.1.3 (1ubuntu1)
    • cmake version 3.28.3
    • ninja version 1.11.1
    • pkg-config version 1.8.1

[✓] Android Studio (version 2024.2)
    • Android Studio at /home/ajthapa/dev/tooling/android-studio
    • Flutter plugin version 83.0.3
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)

[✓] VS Code (version 1.96.4)
    • VS Code at /usr/share/code
    • Flutter extension version 3.102.0

[✓] Connected device (3 available)
    • sdk gphone64 x86 64 (mobile) • emulator-5554 • android-x64    • Android 15 (API 35) (emulator)
    • Linux (desktop)              • linux         • linux-x64      • Ubuntu 24.04.1 LTS 6.8.0-51-generic
    • Chrome (web)                 • chrome        • web-javascript • Google Chrome 131.0.6778.204

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

• No issues found!
Solution

  • you could try this settings. I've recently went through incompatibility issues like you :

    I configured my Flutter JDK Directory on a Java 17 sdk and used these resources :

    https://docs.gradle.org/current/userguide/compatibility.html
    https://services.gradle.org/distributions/ Android getting error: Namespace not specified

    android/app/build.gradle

compileOptions {
  sourceCompatibility JavaVersion.VERSION_17
  targetCompatibility JavaVersion.VERSION_17
}

android/settings.gradle
 
plugins { 
  id "dev.flutter.flutter-plugin-loader" version "1.0.0" 
  id "com.android.application" version "8.5.0" apply false 
  id "org.jetbrains.kotlin.android" version "1.8.0" apply false 
} 

gradle-wrapper.properties 
..
distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-all.zip 
..

    Also you may need this to fix the "Namespace Not Specified" error since Gradle 8 (Android getting error: Namespace not specified)

    build.gradle

subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
// this
subprojects {
    afterEvaluate { project ->
        if (project.hasProperty('android')) {
            project.android {
                if (namespace == null) {
                    namespace project.group
                }
            }
        }
    }
}

    Hope it will help you