Migrating Flutter Android projects to built-in Kotlin

To build a Flutter app for Android, the Android Gradle Plugin (AGP) must be used. To use AGP 9 and later, the following migrations are required.

First, built-in Kotlin is the default in AGP 9 and later. Apps that use the kotlin-android plugin, also known as the Kotlin Gradle Plugin (KGP), will fail to build (Issue #181383). However, the Flutter team has added temporary support for the legacy Kotlin Gradle Plugin in AGP 9 and later (Issue #183909). This allows app and plugin developers to safely build their projects regardless of their migration state.

Second, AGP 9 and later only use the new AGP DSL interfaces. This means any old DSL types will not be recognized. The Flutter team is working on migrating old DSL types to use the new DSL: Issue #180137. In the meantime, the Flutter team has configured the AGP DSL to be compatible with the legacy DSL types (Issue #184838). This ensures app and plugin developers can safely upgrade to AGP 9 and later.

To ensure compatibility, manually migrate all apps and plugins from the legacy KGP to built-in Kotlin. Flutter plans to remove support for applying KGP in a future version (Issue #184837).

To learn more about Android Gradle Plugin, see the Android Gradle Plugin docs.

For app developers: Follow the app developer migration guide.

For plugin authors: Follow the plugin author migration guide.

• Remove support for KGP: In a future version of Flutter, support for applying KGP will be removed (Issue #184837). Migrate apps, plugins, and host apps to keep them building.

• Remove the DSL Gradle property: Once the Flutter team completes the migration to the new AGP DSL, it will remove support for the old DSL (Issue #184839).

Landed in version: 3.44.0-0.1.pre
In stable release: 3.44

Relevant issues:

• Issue #180137: Migrate from old to new AGP DSL
• Issue #181383: Flutter plugins should support AGP 9.0.0
• Issue #183909: Add support for KGP in AGP+
• Issue #184837: Remove support for KGP
• Issue #184838: Disable new AGP DSL flag by default
• Issue #184839: Remove support for old AGP DSL types

The Gradle build files in your app vary based on the Flutter version used when your app was created. Consider staying up to date with the latest version of the build files by periodically running flutter upgrade in your app's directory.