Flutter: Execution failed for task ':games_services:compileDebugKotlin'

Question

I'm using games_services and it was working ok before updating Flutter to latest version.

Error:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':games_services:compileDebugKotlin'.
> Inconsistent JVM-target compatibility detected for tasks 'compileDebugJavaWithJavac' (1.8) and 'compileDebugKotlin' (21).

  Consider using JVM Toolchain: https://kotl.in/gradle/jvm/toolchain
  Learn more about JVM-target validation: https://kotl.in/gradle/jvm/target-validation 

build.gradles:

buildscript {
    ext.kotlin_version = '1.9.23'
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:8.3.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

---

compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

games_services: ^4.0.1

Flutter (Channel stable, 3.19.2, on Microsoft Windows [Version 10.0.19045.4123], locale en-US) • Flutter version 3.19.2 on channel stable at C:\flutter • Upstream repository https://github.com/flutter/flutter.git • Framework revision 7482962148 (10 days ago), 2024-02-27 16:51:22 -0500 • Engine revision 04817c99c9 • Dart version 3.3.0 • DevTools version 2.31.1

Answer 1

Solution You need to ensure that both the Java and Kotlin compilation targets are consistent. Try the following steps:

1. Update Kotlin JVM Target Ensure the Kotlin jvmTarget version matches the one set for Java (1.8):

2. Force JVM Compatibility Update the compileOptions to ensure both Java and Kotlin target the same version:

3. Use JVM Toolchain (Optional, if using Gradle 7.0+) Gradle 7+ introduced the concept of a JVM toolchain, which can help ensure consistent JVM versions across the project:

4. Consider Upgrading to a Higher JVM Target If you're using dependencies that require a higher JVM version (like Java 21), and your project supports it, you can update both Kotlin and Java to target the higher version: