Build Failed In Flutter Project After Cloning To New Device – Unknown Kotlin JVM Target: 21

Introduction

Cloning a Flutter project to a new device can be a convenient way to work on a project from a different location. However, it's not uncommon to encounter issues after cloning a project, especially if the new device has a different setup or configuration. In this article, we'll discuss a common issue that developers may face when cloning a Flutter project to a new device – the "Unknown Kotlin JVM target: 21" error.

Understanding the Error

The "Unknown Kotlin JVM target: 21" error is a common issue that developers may encounter when working with Flutter projects. This error typically occurs when the project is trying to build or run on a device that has a different version of the Kotlin JVM target installed. In this case, the error message indicates that the project is trying to use a Kotlin JVM target version 21, which is not recognized by the device.

Causes of the Error

There are several reasons why the "Unknown Kotlin JVM target: 21" error may occur when cloning a Flutter project to a new device. Some of the possible causes include:

• Different Kotlin JVM target versions: The new device may have a different version of the Kotlin JVM target installed, which is not compatible with the project's requirements.
• Incompatible Android SDK versions: The project may be using an Android SDK version that is not compatible with the device's Android SDK version.
• Missing or corrupted dependencies: The project may be missing or have corrupted dependencies, which can cause the build to fail.
• Incorrect configuration: The project's configuration may be incorrect, which can cause the build to fail.

Solutions to the Error

Fortunately, there are several solutions to the "Unknown Kotlin JVM target: 21" error. Here are some steps you can take to resolve the issue:

1. Update the Kotlin JVM Target

The first step is to update the Kotlin JVM target to a version that is compatible with the device. You can do this by modifying the android/build.gradle file to use a different Kotlin JVM target version.

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

2. Update the Android SDK Version

Another solution is to update the Android SDK version to a version that is compatible with the project's requirements. You can do this by modifying the android/build.gradle file to use a different Android SDK version.

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
    defaultConfig {
        minSdkVersion 21
        targetSdkVersion 30
        compileSdkVersion 30
    }
}

3. Check for Missing or Corrupted Dependencies

Another possible cause of the error is missing or corrupted dependencies. You can check for missing or corrupted dependencies by running the following command:

flutter pub get
``This command will download and install any missing dependencies.
4. Check the Project's Configuration
Finally, you can check the project's configuration to ensure that it is correct. You can do this by checking the android/build.gradle file and the pubspec.yaml file to ensure that they are correctly configured.
Conclusion
In conclusion, the "Unknown Kotlin JVM target: 21" error is a common issue that developers may encounter when cloning a Flutter project to a new device. However, by following the steps outlined in this article, you can resolve the issue and get your project up and running on the new device. Remember to update the Kotlin JVM target, update the Android SDK version, check for missing or corrupted dependencies, and check the project's configuration to ensure that it is correct.
Troubleshooting Tips
Here are some additional troubleshooting tips that you can use to resolve the "Unknown Kotlin JVM target: 21" error:

Check the device's Android SDK version: Make sure that the device's Android SDK version is compatible with the project's requirements.
Check the project's dependencies: Make sure that the project's dependencies are correctly configured and up to date.
Check the project's configuration: Make sure that the project's configuration is correct and up to date.
Try cleaning and rebuilding the project: Try cleaning and rebuilding the project to see if it resolves the issue.

Common Issues and Solutions
Here are some common issues and solutions that you may encounter when cloning a Flutter project to a new device:

Issue: The project is not building due to a missing or corrupted dependency.
Solution: Run the flutter pub get command to download and install any missing dependencies.
Issue: The project is not building due to an incorrect configuration.
Solution: Check the project's configuration and update it as necessary.
Issue: The project is not building due to a different Kotlin JVM target version.
Solution: Update the Kotlin JVM target version to a version that is compatible with the device.

Conclusion


Q: What is the "Unknown Kotlin JVM target: 21" error in Flutter?
A: The "Unknown Kotlin JVM target: 21" error is a common issue that developers may encounter when cloning a Flutter project to a new device. This error typically occurs when the project is trying to build or run on a device that has a different version of the Kotlin JVM target installed.
Q: What are the possible causes of the "Unknown Kotlin JVM target: 21" error?
A: There are several reasons why the "Unknown Kotlin JVM target: 21" error may occur when cloning a Flutter project to a new device. Some of the possible causes include:

Different Kotlin JVM target versions
Incompatible Android SDK versions
Missing or corrupted dependencies
Incorrect configuration

Q: How can I resolve the "Unknown Kotlin JVM target: 21" error?
A: To resolve the "Unknown Kotlin JVM target: 21" error, you can try the following steps:

Update the Kotlin JVM target to a version that is compatible with the device.
Update the Android SDK version to a version that is compatible with the project's requirements.
Check for missing or corrupted dependencies and run the flutter pub get command to download and install any missing dependencies.
Check the project's configuration and update it as necessary.

Q: What are some common issues and solutions that I may encounter when cloning a Flutter project to a new device?
A: Here are some common issues and solutions that you may encounter when cloning a Flutter project to a new device:

Issue: The project is not building due to a missing or corrupted dependency.
Solution: Run the flutter pub get command to download and install any missing dependencies.
Issue: The project is not building due to an incorrect configuration.
Solution: Check the project's configuration and update it as necessary.
Issue: The project is not building due to a different Kotlin JVM target version.
Solution: Update the Kotlin JVM target version to a version that is compatible with the device.

Q: How can I troubleshoot the "Unknown Kotlin JVM target: 21" error?
A: Here are some additional troubleshooting tips that you can use to resolve the "Unknown Kotlin JVM target: 21" error:

Check the device's Android SDK version to ensure that it is compatible with the project's requirements.
Check the project's dependencies to ensure that they are correctly configured and up to date.
Check the project's configuration to ensure that it is correct and up to date.
Try cleaning and rebuilding the project to see if it resolves the issue.

Q: What are some best practices for cloning a Flutter project to a new device?
A: Here are some best practices for cloning a Flutter project to a new device:

Make sure that the device has the correct version of the Android SDK installed.
Make sure that the project's dependencies are correctly configured and up to date.
Make sure that the project's configuration is correct and up to date.
Try cleaning and rebuilding the project to ensure that it is working correctly.

Q: Can I use a different Kotlin JVM target version in my Flutter project?
A: Yes, you can use a different Kotlin JVM target version in your Flutter project. However, you will need to update the project's configuration to use the new version.
Q: How can I update the Kotlin JVM target version in my Flutter project?
A: To update the Kotlin JVM target version in your Flutter project, you can modify the android/build.gradle file to use a different Kotlin JVM target version.
android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}
</code></pre>
<h2><strong>Conclusion</strong></h2>
<p>In conclusion, the &quot;Unknown Kotlin JVM target: 21&quot; error is a common issue that developers may encounter when cloning a Flutter project to a new device. By following the steps outlined in this article, you can resolve the issue and get your project up and running on the new device. Remember to update the Kotlin JVM target, update the Android SDK version, check for missing or corrupted dependencies, and check the project's configuration to ensure that it is correct.</p>