'warning: Kotlin runtime JAR files in the classpath should have the same version

I get the following warning, but I'm not sure where v1.0.6 resides.

Is it possible this error comes from a Kotlin library somehow including an old Kotlin version?

Any ideas how to fix it or at least how can I follow the suggestion to make kotlin-reflect explicit (1.1) ?

kotlin

Solution 1:^[1]

firstly, figure out the reason by the gradle script below

./gradlew app:dependencies

(change app to your gradle module name)

+--- project :common
|    +--- org.jetbrains.kotlin:kotlin-stdlib:1.3.61
|    |    +--- org.jetbrains.kotlin:kotlin-stdlib-common:1.3.61
|    |    \--- org.jetbrains:annotations:13.0
|    +--- org.jetbrains.kotlinx:kotlinx-coroutines-core-common:1.3.3
|    |    \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.3.61
|    +--- org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:0.12.0 -> 0.14.0
|    |    \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.3.60 -> 1.3.61

Then, the dependency tree will be shown. check which dependency use the issue dependency.

If you found the dependency, decide how to solve it.

upgrade the dependency's version(the dependency's latest version may refer to latest issue dependency's version)
or exclude the issue dependency from the dependency
or follow other answers.

I'm not sure what is the best way. kindly just refer to it.

Solution 2:^[2]

I fixed warning by overwriting kotlin version used in my app

configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        def requested = details.requested
        if (requested.group == 'org.jetbrains.kotlin' && requested.name == 'kotlin-reflect') {
            details.useVersion kotlin_version
        }
    }
}

e.g. kotlin_version = 1.3.0

Solution 3:^[3]

it happens when you are using the dagger in a kotlin project(android) and you have the kotlin version to be 1.7 i.e

implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

all you have to do is add the dependency below to your app build gradle level

  implementation "org.jetbrains.kotlin:kotlin-reflect:1.3.50"

Solution 4:^[4]

replace this

  implementation 'org.jetbrains.kotlin:kotlin-stdlib:1.4.30'

with

implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.4.30'

the version of library should be same as plugin in project level

 classpath org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.30

Solution 5:^[5]

Make sure you use the same version of stdlib-jdk7 & kotlin-gradle-plugin dependencies to avoid warnings.
You can refere below example where stdlib-jdk7 & kotlin-gradle-plugin both have the same version

app-level build.gradle file

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.4.0"
    ...
}

project-level build.gradle file

buildscript {
    dependencies {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.0" 
         ...
    }

}

Solution 6:^[6]

The Kotlin version in build.gradle and the one bundled with your IDE are of different versions. Check the kotlin version in build.gradle (app) and in Tools -> Kotlin -> Configure Kotlin Plugin Updates.

Solution 7:^[7]

When this happens for the Lint task, one can list the dependencies with:

./gradlew -q dependencies app:dependencies --configuration lintClassPath

Which shows that eg. kotlin-stdlib-jdk8:1.4.32 is being used:

 +--- org.jetbrains.kotlin:kotlin-reflect:1.4.32 (*)
 \--- org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.4.32 (*)

I've wrote a Gradle script, which equalizes all the Kotlin library versions:

// Runtime JAR files in the classpath should have the same version.
configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        def kotlinVersion = "1.6.0"
        def requested = details.requested
        if (requested.group == 'org.jetbrains.kotlin') {
            List<String> list = ['kotlin-stdlib', 'kotlin-stdlib-jdk7', 'kotlin-stdlib-jdk8', 'kotlin-stdlib-common']
            if (list.contains(requested.name)) { details.useVersion kotlinVersion }
        }
    }
}

There is no other way, because some older versions are being pulled in by build tools.
One likely could also add kotlin-reflect into the List<String> list (not tested).

Solution 8:^[8]

For flutter initialized project, I commented this line to refer the already available lib

dependencies {
    // implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

and this was gone:

w: Some runtime JAR files in the classpath have an incompatible version. Consider removing them from the classpath

w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:

Solution 9:^[9]

@Photo Point's comment from this answer is what worked for me

configurations.all {
    resolutionStrategy {
        eachDependency {
            if ((requested.group == "org.jetbrains.kotlin") && (!requested.name.startsWith("kotlin-gradle"))) { useVersion(kotlin_version) }
        }
    }
}

And added app-level build.gradle file:

"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

Hope this helps as this drove me nuts for some time!

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2	Vlad
Solution 3	Musa Abdul Wadud
Solution 4	Mubashir Murtaza
Solution 5	Niral Dhameliya
Solution 6	rohegde7
Solution 7
Solution 8
Solution 9	mangu23

'warning: Kotlin runtime JAR files in the classpath should have the same version

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]

Solution 6:[6]

Solution 7:[7]

Solution 8:[8]

Solution 9:[9]