I am using Plugin.InAppBilling for subscription in my MAUI application. For the Android part I need to do Acknowledgement after successful purchase.

Option 1: ConsumePurchaseAsync

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);
    if (!consumed)
    {
        Debug.WriteLine("Purchase consumption/acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

But I am getting below exception:

16:05:10:848    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
16:05:10:848       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:05:10:848    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 371
16:05:10:909    The thread 25 has exited with code 0 (0x0).

Exception is on the below line:

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);

Option 2: DependencyService

Created an interface: IPurchaseAcknowledgment

public interface IPurchaseAcknowledgment
{
    Task<bool> AcknowledgePurchaseAsync(string purchaseToken);
}

Implemented IPurchaseAcknowledgment on MainActivity:

public class MainActivity : MauiAppCompatActivity, IPurchaseAcknowledgment
{
    /// <summary>
    /// Acknowledge purchase using Google Play BillingClient
    /// </summary>
    public async Task<bool> AcknowledgePurchaseAsync(string purchaseToken)
    {
        var billingClient = BillingClient.NewBuilder(Android.App.Application.Context)
            .SetListener(new PurchaseUpdateListener()) // You can implement your own listener if needed
            .EnablePendingPurchases()
            .Build();

        // Connect to the BillingClient
        var billingConnectionTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.StartConnection(new BillingClientStateListener(
            onBillingSetupFinished: billingResult => billingConnectionTaskCompletionSource.SetResult(billingResult),
            onBillingServiceDisconnected: () => billingConnectionTaskCompletionSource.SetException(new System.Exception("Billing service disconnected"))
        ));

        var connectionResult = await billingConnectionTaskCompletionSource.Task;
        if (connectionResult.ResponseCode != BillingResponseCode.Ok)
        {
            return false; // Connection failed
        }

        // Acknowledge the purchase
        var acknowledgeParams = AcknowledgePurchaseParams.NewBuilder()
            .SetPurchaseToken(purchaseToken)
            .Build();

        var acknowledgeTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.AcknowledgePurchase(acknowledgeParams, new AcknowledgePurchaseResponseListener(
            result => acknowledgeTaskCompletionSource.SetResult(result)
        ));

        var acknowledgeResult = await acknowledgeTaskCompletionSource.Task;

        // End connection
        billingClient.EndConnection();

        return acknowledgeResult.ResponseCode == BillingResponseCode.Ok;
    }

    /// <summary>
    /// Listener for purchase updates (can be extended if required)
    /// </summary>
    private class PurchaseUpdateListener : Java.Lang.Object, IPurchasesUpdatedListener
    {
        public void OnPurchasesUpdated(BillingResult billingResult, IList<Purchase> purchases)
        {
            // Handle purchase updates here if needed
        }
    }

    /// <summary>
    /// Listener for billing client state
    /// </summary>
    private class BillingClientStateListener : Java.Lang.Object, IBillingClientStateListener
    {
        private readonly System.Action<BillingResult> onBillingSetupFinished;
        private readonly System.Action onBillingServiceDisconnected;

        public BillingClientStateListener(System.Action<BillingResult> onBillingSetupFinished, System.Action onBillingServiceDisconnected)
        {
            this.onBillingSetupFinished = onBillingSetupFinished;
            this.onBillingServiceDisconnected = onBillingServiceDisconnected;
        }

        public void OnBillingSetupFinished(BillingResult billingResult)
        {
            onBillingSetupFinished?.Invoke(billingResult);
        }

        public void OnBillingServiceDisconnected()
        {
            onBillingServiceDisconnected?.Invoke();
        }
    }

    /// <summary>
    /// Listener for acknowledge purchase response
    /// </summary>
    private class AcknowledgePurchaseResponseListener : Java.Lang.Object, IAcknowledgePurchaseResponseListener
    {
        private readonly System.Action<BillingResult> onAcknowledgeResponse;

        public AcknowledgePurchaseResponseListener(System.Action<BillingResult> onAcknowledgeResponse)
        {
            this.onAcknowledgeResponse = onAcknowledgeResponse;
        }

        public void OnAcknowledgePurchaseResponse(BillingResult billingResult)
        {
            onAcknowledgeResponse?.Invoke(billingResult);
        }
    }
}

Finally after plan purchase:

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var acknowledgmentService = DependencyService.Get<IPurchaseAcknowledgment>();
    var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

    if (!acknowledged)
    {
        Debug.WriteLine("Purchase acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

But getting below exception:

16:23:24:835    [0:] exception:>>System.NullReferenceException: Object reference not set to an instance of an object.
16:23:24:835       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:23:24:835    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 383

Exception is on the below line:

var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

Is there any other solution?

UPDATE

I tried like below:

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(purchase.ProductId, purchase.TransactionIdentifier);

But getting below exception:

12:43:02:766    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
12:43:02:766       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
12:43:02:766    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 372

I am using Plugin.InAppBilling for subscription in my MAUI application. For the Android part I need to do Acknowledgement after successful purchase.

Option 1: ConsumePurchaseAsync

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);
    if (!consumed)
    {
        Debug.WriteLine("Purchase consumption/acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

But I am getting below exception:

16:05:10:848    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
16:05:10:848       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:05:10:848    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 371
16:05:10:909    The thread 25 has exited with code 0 (0x0).

Exception is on the below line:

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);

Option 2: DependencyService

Created an interface: IPurchaseAcknowledgment

public interface IPurchaseAcknowledgment
{
    Task<bool> AcknowledgePurchaseAsync(string purchaseToken);
}

Implemented IPurchaseAcknowledgment on MainActivity:

public class MainActivity : MauiAppCompatActivity, IPurchaseAcknowledgment
{
    /// <summary>
    /// Acknowledge purchase using Google Play BillingClient
    /// </summary>
    public async Task<bool> AcknowledgePurchaseAsync(string purchaseToken)
    {
        var billingClient = BillingClient.NewBuilder(Android.App.Application.Context)
            .SetListener(new PurchaseUpdateListener()) // You can implement your own listener if needed
            .EnablePendingPurchases()
            .Build();

        // Connect to the BillingClient
        var billingConnectionTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.StartConnection(new BillingClientStateListener(
            onBillingSetupFinished: billingResult => billingConnectionTaskCompletionSource.SetResult(billingResult),
            onBillingServiceDisconnected: () => billingConnectionTaskCompletionSource.SetException(new System.Exception("Billing service disconnected"))
        ));

        var connectionResult = await billingConnectionTaskCompletionSource.Task;
        if (connectionResult.ResponseCode != BillingResponseCode.Ok)
        {
            return false; // Connection failed
        }

        // Acknowledge the purchase
        var acknowledgeParams = AcknowledgePurchaseParams.NewBuilder()
            .SetPurchaseToken(purchaseToken)
            .Build();

        var acknowledgeTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.AcknowledgePurchase(acknowledgeParams, new AcknowledgePurchaseResponseListener(
            result => acknowledgeTaskCompletionSource.SetResult(result)
        ));

        var acknowledgeResult = await acknowledgeTaskCompletionSource.Task;

        // End connection
        billingClient.EndConnection();

        return acknowledgeResult.ResponseCode == BillingResponseCode.Ok;
    }

    /// <summary>
    /// Listener for purchase updates (can be extended if required)
    /// </summary>
    private class PurchaseUpdateListener : Java.Lang.Object, IPurchasesUpdatedListener
    {
        public void OnPurchasesUpdated(BillingResult billingResult, IList<Purchase> purchases)
        {
            // Handle purchase updates here if needed
        }
    }

    /// <summary>
    /// Listener for billing client state
    /// </summary>
    private class BillingClientStateListener : Java.Lang.Object, IBillingClientStateListener
    {
        private readonly System.Action<BillingResult> onBillingSetupFinished;
        private readonly System.Action onBillingServiceDisconnected;

        public BillingClientStateListener(System.Action<BillingResult> onBillingSetupFinished, System.Action onBillingServiceDisconnected)
        {
            this.onBillingSetupFinished = onBillingSetupFinished;
            this.onBillingServiceDisconnected = onBillingServiceDisconnected;
        }

        public void OnBillingSetupFinished(BillingResult billingResult)
        {
            onBillingSetupFinished?.Invoke(billingResult);
        }

        public void OnBillingServiceDisconnected()
        {
            onBillingServiceDisconnected?.Invoke();
        }
    }

    /// <summary>
    /// Listener for acknowledge purchase response
    /// </summary>
    private class AcknowledgePurchaseResponseListener : Java.Lang.Object, IAcknowledgePurchaseResponseListener
    {
        private readonly System.Action<BillingResult> onAcknowledgeResponse;

        public AcknowledgePurchaseResponseListener(System.Action<BillingResult> onAcknowledgeResponse)
        {
            this.onAcknowledgeResponse = onAcknowledgeResponse;
        }

        public void OnAcknowledgePurchaseResponse(BillingResult billingResult)
        {
            onAcknowledgeResponse?.Invoke(billingResult);
        }
    }
}

Finally after plan purchase:

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var acknowledgmentService = DependencyService.Get<IPurchaseAcknowledgment>();
    var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

    if (!acknowledged)
    {
        Debug.WriteLine("Purchase acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

But getting below exception:

16:23:24:835    [0:] exception:>>System.NullReferenceException: Object reference not set to an instance of an object.
16:23:24:835       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:23:24:835    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 383

Exception is on the below line:

var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

Is there any other solution?

UPDATE

I tried like below:

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(purchase.ProductId, purchase.TransactionIdentifier);

But getting below exception:

12:43:02:766    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
12:43:02:766       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
12:43:02:766    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 372

• maui

• Did you check if purchase.State == PurchaseState.Purchased? In addition, you can check the sample code : PurchaseConsumable. – Liyun Zhang - MSFT Commented Jan 20 at 7:04
• @LiyunZhang-MSFT Yes purchase.State == PurchaseState.Purchased is success and I am able to view the purchase.PurchaseToken and purchase.Id. – Matthew Pans Commented Jan 20 at 7:14
• @LiyunZhang-MSFT I have updated the acknowledgement code like this: var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(purchase.ProductId, purchase.TransactionIdentifier); but getting Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase – Matthew Pans Commented Jan 20 at 7:16
• @LiyunZhang-MSFT Question edited with recent findings. – Matthew Pans Commented Jan 20 at 7:18
• Have you accepted the test program invitation? – Liyun Zhang - MSFT Commented Jan 20 at 7:39

1 Answer 1

Im using v 7.1.3 and after calling the purchase Like this with my own internal productId:

purchase = await CrossInAppBilling.Current.PurchaseAsync(productId.ToString(), ItemType.Subscription);

i do the acknowledge like this:

//possibility that a null came through.
if (purchase == null) {
    //did not purchase
    return false;
}else if (purchase.State == PurchaseState.Purchased) {
    #if ANDROID
    // only need to finalize if on Android unless you turn off auto finalize on iOS
    //V 7.1.3

    IEnumerable<(string, bool)> ack;
    ack = await CrossInAppBilling.Current.FinalizePurchaseAsync(purchase.TransactionIdentifier);
    // TODO: Handle if acknowledge was successful or not
    #endif
}