Resolve Kotlin Binary Version Mismatch Errors in Android Projects

Introduction

If you're developing Android applications using Kotlin, you might encounter an error related to Kotlin binary version mismatches. This error typically looks something like this:

The binary version of its metadata is 2.1.0, expected version is 1.9.0.

In this blog post, we'll explore what this error means and how to resolve it.

Understanding the Error

The error message indicates that the binary version of some Kotlin modules in your project does not match the expected version. This mismatch can cause your build to fail. For example, you might see an error like this:

Task :app:compileDebugKotlin
e: file:///C:/Users/username/.gradle/caches/transformed/play-services-measurement-impl-api.jar!/META-INF/module.kotlin_moduleModule was compiled with an incompatible version of Kotlin. The binary version of its metadata is 2.1.0, expected version is 1.9.0.
    

This means that the module play-services-measurement-impl-api was compiled with Kotlin 2.1.0, but your project is using Kotlin 1.9.0.

Solution

To resolve this issue, you need to ensure that all modules and dependencies in your project use the same Kotlin version. Here are the steps to fix the issue:

1. Update Kotlin Version

First, update your project's Kotlin version to match the version used by the conflicting modules. In this case, we need to update to Kotlin 2.1.0. Open your build.gradle file and make the following changes:

ext.kotlin_version = '2.1.0'
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    

2. Update core-ktx Dependency

Next, update the androidx.core:core-ktx dependency to its latest version, which is compatible with Kotlin 2.1.0. Add or update the following line in your build.gradle file:

implementation "androidx.core:core-ktx:1.15.0"
    

3. Ensure Consistency Across Dependencies

Make sure all other dependencies in your project are compatible with Kotlin 2.1.0. You can use the dependency resolution strategy to enforce a specific Kotlin version for all dependencies:

configurations.all {
    resolutionStrategy {
        force 'org.jetbrains.kotlin:kotlin-stdlib:2.1.0'
    }
}
    

4. Clean and Rebuild the Project

After updating the Kotlin version and dependencies, clear the build, rebuild your project, and run it on a real device or create packages to ensure all changes take effect.

5. Update Dependencies in TOML Files

For users who manage their dependencies using TOML files, the process is similar. Update the Kotlin version and dependencies in your gradle.properties or another configuration TOML file where versions are specified. Here's an example of how to specify the Kotlin version and the core-ktx dependency for the latest Android Studio users:

[versions]
kotlin = "2.1.0"
kotlinStdlib = "2.1.0"
coreKtx = "1.15.0"

[libraries]
androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib", version.ref = "kotlinStdlib" }

[plugins]
kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
    

After updating your dependencies, clear the build, rebuild your project, and run it on a real device or create packages to apply the changes.

Conclusion

Kotlin version mismatches can be frustrating, but they are usually straightforward to resolve by ensuring all modules and dependencies use the same Kotlin version. By following the steps outlined in this post, you can quickly get your project back on track.

Happy coding!