Flutter - IAP error code 6 with message "the item you were attempting to purchase could not be found"

I am performing in app purchase in my app. I am using Flutter-In-App-Purchase Plugin to implement IAP feature. Following is my code to implement IAP.

class InApp extends StatefulWidget {
  @override
  _InAppState createState() => _InAppState();
}

class _InAppState extends State<InApp> {
  StreamSubscription _purchaseUpdatedSubscription;
  StreamSubscription _purchaseErrorSubscription;
  StreamSubscription _conectionSubscription;
  final List<String> _productLists = Platform.isAndroid
      ? ["Buy Book"]
      : ["Buy Book"];

  List<IAPItem> _items = [];
  List<PurchasedItem> _purchases = [];

  @override
  void initState() {
    super.initState();
    initPlatformState();
  }

  @override
  void dispose() {
    if (_conectionSubscription != null) {
      _conectionSubscription.cancel();
      _conectionSubscription = null;
    }
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    // prepare
    var result = await FlutterInappPurchase.instance.initConnection;
    print('result: $result');

    if (!mounted) return;


    _conectionSubscription =
        FlutterInappPurchase.connectionUpdated.listen((connected) {
      print('connected: $connected');
    });

    _purchaseUpdatedSubscription =
        FlutterInappPurchase.purchaseUpdated.listen((productItem) {
      print('purchase-updated: $productItem');
    });

    _purchaseErrorSubscription =
        FlutterInappPurchase.purchaseError.listen((purchaseError) {
      print('purchase-error: $purchaseError');
    });
  }

  void _requestPurchase(IAPItem item) {
    FlutterInappPurchase.instance.requestPurchase(item.productId);
  }

  Future _getProduct() async {
    List<IAPItem> items = await FlutterInappPurchase.instance.getProducts(_productLists);
    for (var item in items) {
      print('${item.toString()}');
      this._items.add(item);
    }

    setState(() {
      this._items = items;
      this._purchases = [];
    });

    _getPurchases();
  }

  Future _getPurchases() async {
    List<PurchasedItem> items = await FlutterInappPurchase.instance.getAvailablePurchases();
    for (var item in items) {
      print('${item.toString()}');
      this._purchases.add(item);
    }

    setState(() {
      this._items = [];
      this._purchases = items;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: RaisedButton(
          onPressed: () {
            _requestPurchase(_items[0]);
          },
          child: Text("Buy Item"),
        ),
      ),
    );
  }
}

When i click on BuyItem and requestPurchase() method gets called. I gets following error logs and get the error like "the item you were attempting to purchase could not be found"

W/ActivityThread( 8794): handleWindowVisibility: no activity for token android.os.BinderProxy@572f129 W/ProxyBillingActivity( 8794): Activity finished with resultCode 0 and billing's responseCode: 6 W/BillingHelper( 8794): Couldn't find purchase lists, trying to find single data. W/BillingHelper( 8794): Received a bad purchase data. W/BillingHelper( 8794): Couldn't find single purchase data as well. E/DoobooUtils( 8794): Error Code : 6 I/flutter ( 8794): purchase-error: responseCode: 6, debugMessage: , code: E_UNKNOWN, message: An unknown or unexpected error has occured. Please try again later.

Please suggest a solution.

Thanks.

I think your in app product will be in the inactive state.

By default, when you add a managed product in the play console it will be in the inactive state. So just visit your in app products in your google play console account and verify that it is active.

Also, make sure that VersionCode and VersionName of the app you are developing/testing should be atleast the version in the google play developer console/play store.

For flutter you can check your versioning in the pubspec.yaml file.