I get the warning: observer object was not disposed manually with Dispose() multiple times when I start debugging my iOS project on my iPad Air

Question

I get the warning: observer object was not disposed manually with Dispose() multiple times when I start debugging my iOS project on my iPad Air

Kim Strasser 1,956

I get many messages(in debug mode) in the Visual Studio Output window that I don´t understand and I don´t know where these messages come from when I debug my iOS project on my iPad Air. My iPad Air is connected to my MacBook Air.

I get the warning: observer object was not disposed manually with Dispose(). But I don´t know where this warning comes from because I only find this code in my project when I search for "observer" in my code. And here I already use .Dispose():

observer = NSNotificationCenter.DefaultCenter.AddObserver(new NSString("AVPlayerItemDidPlayToEndTimeNotification"), async (notification) =>
   {
       PlayerViewController.DismissViewController(true, null); // add observer to catch the ending event
       // Dispose AVPlayer and AVPlayerViewController
       PlayerViewController.Player.Dispose();
       PlayerViewController.Dispose();

       // Remove observer
       NSNotificationCenter.DefaultCenter.RemoveObserver(observer);

Why am I getting the warning observer object was not disposed manually with Dispose()? How can I find out which code triggered the warnings?

I have uploaded my iOS project in Release mode to TestFlight and until now it didn´t crashed. Is it possible that my iOS project won´t crash even if I get these warnings in debug mode?

INFO: Connecting to HotReload local tunnel stream from remote client... INFO: Connecting to HotReload local tunnel stream from device... INFO: [iOS HotReload] Connected to "iPad von Kim" over USB on port 11000. INFO: Connecting to remote HotReload local tunnel on port 57871... INFO: error in connection_block_invoke_2: Connection invalid INFO: 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() INFO: 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.264 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() INFO: 2025-12-13 11:44:12.262 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.262 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() INFO: 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 2025-12-13 11:44:12.263 ProjectiOS[667:22917] Warning: observer object was not disposed manually with Dispose() 'Project' (Mono: Default Domain): Loaded 'C:\ProjectTestVSInsiders\Project\ProjectiOS\bin\Debug\net10.0-ios\ios-arm64\Microsoft.Maui.Controls.HotReload.Forms.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'Project' (Mono: Default Domain): Loaded 'C:\ProjectTestVSInsiders\Project\ProjectiOS\bin\Debug\net10.0-ios\ios-arm64\Microsoft.VisualStudio.DesignTools.XamlTapContract.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. Exception thrown: 'System.NullReferenceException' in ProjectiOS.dll Object reference not set to an instance of an object. An error occurred in the vsdbg debug session of project 'C:\ProjectTestVSInsiders\Project\ProjectiOS\ProjectiOS.csproj': Exception thrown: 'System.NullReferenceException' in ProjectiOS.dll Object reference not set to an instance of an object. The thread '.NET TP Worker' (24) has exited with code 0 (0x0). INFO: 2025-12-13 11:44:33.283 ProjectiOS[667:22844] Unbalanced calls to begin/end appearance transitions for <Microsoft_Xna_Framework_iOSGameViewController: 0x105d45ea0>. INFO: 2025-12-13 11:44:33.957 ProjectiOS[667:22844] -[AVAsset loadValuesAsynchronouslyForKeys:completionHandler:] invoked with unrecognized keys ( albumName, author, title, artist ). INFO: 2025-12-13 11:44:33.974 ProjectiOS[667:23236] -[AVAsset loadValuesAsynchronouslyForKeys:completionHandler:] invoked with unrecognized keys ( artwork ). INFO: 2025-12-13 11:44:34.984 ProjectiOS[667:23236] Value cannot be null. (Parameter 'data') The program 'Project' has exited with code 0 (0x0). The vsdbg debug session for project 'C:\ProjectTestVSInsiders\Project\ProjectiOS\ProjectiOS.csproj' has been stopped Failed to Stop app: An error occurred on client IDB180345 while executing a reply for topic xvs/idb/stop-app INFO: Disposing input and output streams... INFO: Disposing input and output streams... INFO: Disposing input and output streams... INFO: Disposing input and output streams... INFO: The debug console output is no longer available for reading INFO: The debug streams are no longer available for reading or writing INFO: Wrote 'exit process' to the debug stream INFO: Disposing console and debugger streams... INFO: Closing HotReload local tunnel connection from device INFO: Closing debug connection from device (USB) INFO: Closing debug connection from remote debugger (TCP) INFO: The debug streams are no longer available for reading or writing The app has been terminated.

2 answers

Your answer

Answer 1

Michael Le (WICLOUD CORPORATION) 9,875 Microsoft External Staff Moderator

Hello @Kim Strasser ,

Try searching for these patterns across your entire solution:

AddObserver
NSNotificationCenter
AVPlayerViewController (video playback often creates internal observers)
Any custom renderers or handlers
Third-party libraries that might use notification observers

You might also have observers created by MAUI/Xamarin.Forms controls themselves, especially if you’re working with media playback components.

Issue with your current code

There’s a problem with the disposal order:

observer = NSNotificationCenter.DefaultCenter.AddObserver(
    new NSString("AVPlayerItemDidPlayToEndTimeNotification"), async (notification) =>
{
    PlayerViewController.DismissViewController(true, null);
    PlayerViewController.Player.Dispose();
    PlayerViewController.Dispose();
    NSNotificationCenter.DefaultCenter.RemoveObserver(observer);
});

You’re removing the observer with RemoveObserver, but you’re not calling observer.Dispose() on the observer object itself. Removing it from the notification center isn’t the same as disposing the NSObject wrapper.

Proper disposal pattern

You should implement this at the class level where your observer lives:

private NSObject observer;

// When setting up your observer
observer = NSNotificationCenter.DefaultCenter.AddObserver(
    AVPlayerItem.DidPlayToEndTimeNotification, 
    HandleVideoEnd);

// In your cleanup code (like Dispose or view disappearing)
public void Dispose()
{
    if (observer != null)
    {
        NSNotificationCenter.DefaultCenter.RemoveObserver(observer);
        observer.Dispose(); // This is the critical part you’re missing
        observer = null;
    }
}

Will it crash in production?

Your app might not crash immediately, but you’re leaking memory. Each undisposed observer keeps objects in memory. Over time, especially if users navigate to views that create these observers repeatedly, memory usage will grow and could eventually cause crashes or performance issues.

Debugging steps

Use Visual Studio’s memory profiler to track object allocations.
Check if AVPlayerViewController or AVPlayer creates internal observers that need explicit disposal.
Look for any custom renderers or platform-specific code that might create observers.
Review any media playback libraries you’re using.

Hope this helps, and happy holidays.

Kim Strasser 1,956

Should I execute the following two lines before I call public void Dispose() ?

PlayerViewController.Player.Dispose();     
PlayerViewController.Dispose();

PlayerViewController.DismissViewController(true, null);
PlayerViewController.Player.Dispose();    
PlayerViewController.Dispose();
Dispose();

public void Dispose()
{
    if (observer != null)
    {
        NSNotificationCenter.DefaultCenter.RemoveObserver(observer);
        observer.Dispose(); // This is the critical part you’re missing
        observer = null;
    }
}

Michael Le (WICLOUD CORPORATION) 9,875 Reputation points Microsoft External Staff Moderator

2025-12-16T09:50:48.27+00:00

Yes, that order is correct.
Kim Strasser 1,956 Reputation points

2025-12-16T22:52:53.14+00:00

What does the number [754:26256] mean?

INFO: 2025-12-16 23:47:04.456 ProjectiOS[754:26256] Warning: observer object was not disposed manually with Dispose() 2025-12-16 23:47:04.457 ProjectiOS[754:26256] Warning: observer object was not disposed manually with Dispose() 2025-12-16 23:47:04.457 ProjectiOS[754:26256] Warning: observer object was not disposed manually with Dispose() 2025-12-16 23:47:04.457 ProjectiOS[754:26256] Warning: observer object was not disposed manually with Dispose()
Michael Le (WICLOUD CORPORATION) 9,875 Reputation points Microsoft External Staff Moderator

2025-12-17T02:08:01.4666667+00:00
The format [754:26256] represents [process_id:thread_id].

754 is your app's process ID on the iPad.

26256 is the specific thread ID where the warning occurred.
Kim Strasser 1,956 Reputation points

2026-01-04T20:47:01.1966667+00:00

I still get the warning: observer object was not disposed manually with Dispose() multiple times but the warning is not always displayed in the Visual Studio output window. I use the following setting in the output window Show output from: Debug.Is it necessary to use .Dispose() after I called UNUserNotificationCenter? I call UNUserNotificationCenter particularly in Program.cs when I start my application. I use it to check if the push notifications are enabled on the device and when the dialog is displayed where the user can allow or don´t allow to get push notifications.I can post the code here if you want to have a look at it.
Michael Le (WICLOUD CORPORATION) 9,875 Reputation points Microsoft External Staff Moderator

2026-01-05T02:26:16.2566667+00:00

Well, UNUserNotificationCenter itself doesn't really need disposal since it's a singleton, but if you're setting a delegate or adding observers as part of that setup, those do need cleanup.

It would be nice if you can post the relevent code here so I can give you a more specific answer.

Kim Strasser 1,956

I found delegate in Program.cs and UserNotificationCenterDelegate in UserNotificationCenterDelegate.cs:

using System;
using Foundation;
using UserNotifications;

namespace MyProjectiOS
{
    public class UserNotificationCenterDelegate : UNUserNotificationCenterDelegate
    {
        [Export("userNotificationCenter:willPresentNotification:withCompletionHandler:")]
        public override void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, Action<UNNotificationPresentationOptions> completionHandler)
        {
            completionHandler(UNNotificationPresentationOptions.Sound | UNNotificationPresentationOptions.Badge | UNNotificationPresentationOptions.Banner | UNNotificationPresentationOptions.List);
        }
    }
}

Program.cs:

using System;
using Foundation;
using UIKit;
using System.Runtime.InteropServices;
using SharedCode;
using MediaManager;
using UserNotifications;

namespace MyProjectiOS
{
    [Register("AppDelegate")]
    class Program : UIApplicationDelegate
    {
        public override UIWindow? Window
        {
            get;
            set;
        }

        private static Game1 game;
        private MyViewController MainViewController;

        internal static void RunGame()
        {
            int w1 = (int)(UIScreen.MainScreen.Bounds.Size.Width * UIScreen.MainScreen.Scale);
            int h1 = (int)(UIScreen.MainScreen.Bounds.Size.Height * UIScreen.MainScreen.Scale);
            game = new Game1(w1, h1);
            game.Run();
        }

        static void Main(string[] args)
        {
            UIApplication.Main(args, null, typeof(MyProjectiOS.Program));
        }

        public override void FinishedLaunching(UIApplication app)
        {
            CrossMediaManager.Current.Init();

            UIApplication.SharedApplication.IdleTimerDisabled = true;

            // Request notification permissions from the user  
            UNUserNotificationCenter.Current.RequestAuthorization(UNAuthorizationOptions.Badge | UNAuthorizationOptions.Sound | UNAuthorizationOptions.Alert, (approved, err) => {
                // Handle approval
                if (approved == false)
                {
                    // REQUEST_P0STNOTIFICATIONS Permission Denied
                }

            });
            UNUserNotificationCenter.Current.Delegate = new UserNotificationCenterDelegate(); //set delegate

            UNUserNotificationCenter.Current.GetNotificationSettings((settings) =>
            {
                if (settings.AuthorizationStatus == UNAuthorizationStatus.NotDetermined || settings.AuthorizationStatus == UNAuthorizationStatus.Denied)
                {
                    InvokeOnMainThread(() =>// in UI thread
                    {
                        var okAlertController = UIAlertController.Create("Title", "go to setting", UIAlertControllerStyle.Alert);

                        //Add Action
                        okAlertController.AddAction(UIAlertAction.Create("Ok", UIAlertActionStyle.Default, (e) =>
                        {
                            var nurl = NSUrl.FromString(UIApplication.OpenNotificationSettingsUrl);
                            UIApplication.SharedApplication.OpenUrl(nurl!, new NSDictionary(), null); // This line of code will make app go to Notification page. If you test on simulator, the app will jump to Settings page.
                        }));

                        okAlertController.AddAction(UIAlertAction.Create("Cancel", UIAlertActionStyle.Cancel, null));

                        try
                        {
                            UIApplication.SharedApplication.Delegate.GetWindow().RootViewController!.PresentViewController(okAlertController, true, null); //window.RootViewController might be null
                        }
                        catch(Exception ex)
                        {
                        }

                    });
                }
                else
                {
                }
            });
          
            UIApplication.SharedApplication.RegisterForRemoteNotifications();
           
            var Window = new UIWindow(UIScreen.MainScreen.Bounds);
            MainViewController = new MyViewController();
            Window.RootViewController = MainViewController;
            Window.MakeKeyAndVisible();

            RunGame();
        }

        public string DeviceToken { get; set; }
        public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
        {
            byte[] result = new byte[deviceToken.Length];
            Marshal.Copy(deviceToken.Bytes, result, 0, (int)deviceToken.Length);
            DeviceToken = BitConverter.ToString(result).Replace("-", "");

            // Get previous device token
            var oldDeviceToken = NSUserDefaults.StandardUserDefaults.StringForKey("PushDeviceToken");
            // Has the token changed?
            if (string.IsNullOrEmpty(oldDeviceToken) || !oldDeviceToken.Equals(DeviceToken))
            {
            
            }
            // Save new device token
            NSUserDefaults.StandardUserDefaults.SetString(DeviceToken, "PushDeviceToken");
        }

        public override void FailedToRegisterForRemoteNotifications(UIApplication application, NSError error)
        {         
            var window = UIApplication.SharedApplication.KeyWindow;
            if (window != null)
            {
            var vc = window.RootViewController;
            while (vc.PresentedViewController != null)
            {
                vc = vc.PresentedViewController;
            }

            //Create Alert
            var okAlertController = UIAlertController.Create("Remote Notifications", "Failed to register.", UIAlertControllerStyle.Alert);

            //Add Action
            okAlertController.AddAction(UIAlertAction.Create("Ok", UIAlertActionStyle.Default, null));

            // Present Alert
            vc.PresentViewController(okAlertController, true, null);
            }
            else
            {
      
            }
        }

    }
}

In Game1.cs I use this code:

#elif IOS
                UNUserNotificationCenter.Current.GetNotificationSettings((settings) =>
                {
                if ((settings.AuthorizationStatus == UNAuthorizationStatus.NotDetermined) || (settings.AuthorizationStatus == UNAuthorizationStatus.Denied))
                    Pushnotactiveinsettings = false;
                else
                    Pushnotactiveinsettings = true;
                });
#endif

I get the following exception the first time after my application is installed on the iOS simulator. I don´t get the exception anymore after I have chosen "Allow" in the push notification dialog on the simulator. My application doesn´t crash when I click on the green arrow button to continue debugging.

Screenshot 2026-01-05 102015

at MyPojectiOS.Program.<>c.<FinishedLaunching>b__8_2() in C:\NewTest\MyProject\MyProjectiOS\Program.cs:line 72 at Foundation.NSActionDispatcher.Apply() at UIKit.UIApplication.xamarin_UIApplicationMain(Int32 argc, IntPtr argv, IntPtr principalClassName, IntPtr delegateClassName, IntPtr* gchandle) at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) at MyProjectiOS.Program.Main(String[] args) in C:\NewTest\MyProject\MyProjectiOS\Program.cs:line 33

Michael Le (WICLOUD CORPORATION) 9,875 Microsoft External Staff Moderator

In your FinishedLaunching method, you’re creating a new delegate instance without keeping a reference to it.

Although this method should only be called once, it’s safer to clean up the delegate when the app terminates.

UNUserNotificationCenter.Current.Delegate = new UserNotificationCenterDelegate();

You could consider this approach:

Store the delegate as a field

// Add this at the class level in Program.cs
private UserNotificationCenterDelegate _notificationDelegate;

public override void FinishedLaunching(UIApplication app)
{
    CrossMediaManager.Current.Init();
    UIApplication.SharedApplication.IdleTimerDisabled = true;

    // Create and store the delegate
    _notificationDelegate = new UserNotificationCenterDelegate();

    UNUserNotificationCenter.Current.RequestAuthorization(
        UNAuthorizationOptions.Badge | UNAuthorizationOptions.Sound | UNAuthorizationOptions.Alert, 
        (approved, err) => {
            if (!approved)
            {
                // Handle denial
            }
        });

    // Use the stored reference
    UNUserNotificationCenter.Current.Delegate = _notificationDelegate;

    // Rest of your existing code...
}

Clean it up when the app terminates

(assuming you have a termination handler)

public override void WillTerminate(UIApplication application)
{
    if (_notificationDelegate != null)
    {
        UNUserNotificationCenter.Current.Delegate = null;
        _notificationDelegate = null;
    }
}

Null reference exception

Add a null check before presenting the alert, looking something like this:

var rootVC = UIApplication.SharedApplication.Delegate?.GetWindow()?.RootViewController;

Kim Strasser 1,956 Reputation points

2026-01-05T12:22:07.2133333+00:00
I made the changes and the code in WillTerminate gets executed and _notificationDelegate set to null when I quit my application on the iOS simulator. But after that I get an unhandled exception in this line.

Foundation.You_Should_Not_Call_base_In_This_Method

static void Main(string[] args) { UIApplication.Main(args, null, typeof(MyProjectiOS.Program)); }

at UIKit.UIApplication.xamarin_UIApplicationMain(Int32 argc, IntPtr argv, IntPtr principalClassName, IntPtr delegateClassName, IntPtr* gchandle) at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) at MyProjectiOS.Program.Main(String[] args) in C:\NewTest\MyProject\MyProjectiOS\Program.cs:line 34
Michael Le (WICLOUD CORPORATION) 9,875 Reputation points Microsoft External Staff Moderator

2026-01-07T10:38:34.6+00:00
You should remove this line in WillTerminate method and try again:

base.WillTerminate(application);

Answer 2

The warning you are encountering, "observer object was not disposed manually with Dispose()," indicates that there are instances of observers that are not being properly disposed of in your code. This can occur if you add observers to the NSNotificationCenter but do not remove them appropriately, leading to potential memory leaks.

In your provided code snippet, you are correctly removing the observer after the notification is handled:

NSNotificationCenter.DefaultCenter.RemoveObserver(observer);

However, the warning suggests that there might be other observers in your project that are not being disposed of correctly. Here are a few steps you can take to identify and resolve the issue:

Search for All Observer Instances: Search your entire project for instances where NSNotificationCenter.DefaultCenter.AddObserver is called. Ensure that each observer is paired with a corresponding RemoveObserver call.
Check for Conditional Logic: Make sure that the removal of observers is not conditional or dependent on certain logic that may not always execute.
Use Weak References: Consider using weak references for observers to avoid retaining them unnecessarily. This can help prevent memory leaks without needing to manually dispose of them.
Debugging: You can add logging around your observer additions and removals to track where they are being added and whether they are being removed appropriately. This can help you pinpoint where the issue might be occurring.
Review Other Parts of Your Code: The warning may not originate from the code snippet you provided. Review other parts of your codebase where observers might be added.

Regarding your question about the stability of your app despite these warnings: while your app may not crash in Release mode on TestFlight, it is still advisable to address these warnings. They can lead to memory leaks, which can degrade performance over time or cause crashes under certain conditions. Regular profiling and testing can help catch these issues before they become problematic.

References:

Diagnosing Memory Leaks

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I get the warning: observer object was not disposed manually with Dispose() multiple times when I start debugging my iOS project on my iPad Air

2 answers

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