# Profile data migration

To make it easier to collect data to a Profile, Batch has added two automatic ways to migrate old installation's data on a Profile:

* User will be automatically identified (logged-in) if he had a Batch `custom_user_id` set on the local storage.
* User natives (language/region) and custom data will be automatically migrated to a Profile.

These migrations are triggered when your application on the dashboard is attached to a Project. Concretely this mean that there's two possible scenarios:

* Your app is running on the SDK v1 and is already attached to a Project : migrations will be triggered on the first start running on SDK v2.
* Your app is running on the SDK v2 but not attached to a Project: migrations will be triggered on the first start after your app is attached to a project.

These migrations are enabled by default, but you may want to disable them, to do so add the following before starting the SDK:

{% tabs %}
{% tab title="Kotlin" %}

```kotlin
class YourApp : Application() {
  
  override fun onCreate() {
    super.onCreate()
    // Disable profile's migration
    Batch.disableMigration(
      EnumSet.of( 
        // Whether Batch should automatically identify logged-in user when running the SDK for the first time.
        // This mean user with a custom_user_id will be automatically attached a to a Profile and could be targeted within a Project scope.
        BatchMigration.CUSTOM_ID,  
        // Whether Batch should automatically attach current installation's data (language/region/customDataAttributes...)
        // to the User's Profile when running the SDK for the first time.
        BatchMigration.CUSTOM_DATA
      )
    )
    // Then start the sdk
    Batch.start("YOUR_API_KEY")
    registerActivityLifecycleCallbacks(BatchActivityLifecycleHelper())
  }
}
```

{% endtab %}

{% tab title="Java" %}

```java
public class YourApp extends Application {

  @Override
  public void onCreate() {
    super.onCreate();
    // Disable profile's migration
    Batch.disableMigration(
      EnumSet.of(
        // Whether Batch should automatically identify logged-in user when running the SDK for the first time.
        // This mean user with a custom_user_id will be automatically attached a to a Profile and could be targeted within a Project scope.
        BatchMigration.CUSTOM_ID,
        // Whether Batch should automatically attach current installation's data (language/region/customDataAttributes...)
        // to the User's Profile when running the SDK for the first time.
        BatchMigration.CUSTOM_DATA
      )
    );
    
    // Then start the sdk
    Batch.start("YOUR_API_KEY");
    registerActivityLifecycleCallbacks(new BatchActivityLifecycleHelper());
  }
}
```

{% endtab %}
{% endtabs %}


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