Issue:
When building a react native app for Android, you might suddenly come across the following error.
FAILURE: Build completed with 2 failures.
1: Task failed with an exception.
-----------
* What went wrong:
Execution failed for task ':app:checkDebugDuplicateClasses'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckDuplicatesRunnable
> Duplicate class kotlin.collections.jdk8.CollectionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.internal.jdk7.JDK7PlatformImplementations found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.internal.jdk7.JDK7PlatformImplementations$ReflectSdkVersion found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.internal.jdk8.JDK8PlatformImplementations found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.internal.jdk8.JDK8PlatformImplementations$ReflectSdkVersion found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.io.path.ExperimentalPathApi found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.io.path.PathRelativizer found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.io.path.PathsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.io.path.PathsKt__PathReadWriteKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.io.path.PathsKt__PathUtilsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.jdk7.AutoCloseableKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.6.21)
Duplicate class kotlin.jvm.jdk8.JvmRepeatableKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.random.jdk8.PlatformThreadLocalRandom found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.streams.jdk8.StreamsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$1 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$2 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$3 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$4 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.text.jdk8.RegexExtensionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Duplicate class kotlin.time.jdk8.DurationConversionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21)
Go to the documentation to learn how to <a href="d.android.com/r/tools/classpath-sync-errors">Fix dependency resolution errors</a>.
This error might be caused by a mix-up of different plugins that you use. In my case it suddenly showed up after I implemented a plugin for an InAppBrowser support.
Fix error by adding dependency constraint
In order to fix this issue, you should add a dependencies constraint to the Android build.gradle file inside the React Native Android project.
1. Open app build.gradle file
Open the following file in your text editor or IDE:
./[project-root]/android/app/build.gradle
2. Find dependencies{} section
This file should already contain a “dependencies” section somewhere near the bottom of the file. This section should look something like this:
dependencies {
// The version of react-native is set by the React Native Gradle Plugin
implementation("com.facebook.react:react-android")
}
3. Add constraint
Within the dependencies{} you should add the following constraint. The final dependencies{} section should then look like this:
constraints {
implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.8.0") {
because("kotlin-stdlib-jdk7 is now a part of kotlin-stdlib")
}
implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.8.0") {
because("kotlin-stdlib-jdk8 is now a part of kotlin-stdlib")
}
}
After adding this section, this save the file.
4. Recompile and run project
Now recompile and run the project. The build should now succeed without errors. Optionally you might want to run the following command from the project root, in order to clean the gradle cache:
cd android && ./gradlew clean && ./gradlew build
That should do the trick. Good luck!
Disclaimer: thanks to https://dev.to/retyui/fix-react-native-android-builds-duplicate-class-kotlincollections-found-in-modules-jetified-kotlin-stdlib-180-2ca7 for the investigation and fix!
