Resolving Bytecode Compatibility Issues in IntelliJ

Resolving Bytecode Compatibility Issues in IntelliJ

22 May 2024 Stephan Petzl Leave a comment Tech-Help

When working with Kotlin and Java in IntelliJ, you might encounter an error indicating that bytecode built with JVM target 1.8 cannot be inlined into bytecode built with JVM target 1.6. This issue arises due to inconsistencies in the JVM target versions specified in your project settings. Below, we’ll guide you through the steps to resolve this issue.

Step-by-Step Solution

Modifying build.gradle

The primary method to resolve this issue involves updating your build.gradle file to ensure that all parts of your project are compiled with the same JVM target version. Here’s how you can do it:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8.toString()

Adding the above configuration ensures that both Java and Kotlin code are compiled with JVM target 1.8.

Updating IntelliJ Settings

If modifying the build.gradle file does not resolve the issue, you can also adjust the settings directly in IntelliJ:

  • Open IntelliJ preferences.
  • Navigate to Build, Execution, Deployment > Compiler > Kotlin Compiler.
  • Change the Target JVM version to 1.8.
  • Click Apply and then OK.

For Android Studio users, the settings can be found under Other Settings > Kotlin compiler if using Android Studio version 3.4 or later.

Ensuring Consistency Across Modules

In projects with multiple modules or source sets, it is crucial to ensure that the JVM target is consistently set across all of them. You can achieve this by adding the following snippet to your build.gradle file:

tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
    kotlinOptions {
        jvmTarget = "1.8"

This configuration ensures that every Kotlin compile task targets JVM 1.8, maintaining consistency across your project.

Additional Resources

For more detailed guides on related topics, you can refer to the following articles:

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