ObjectDisposedException when Unloaded triggers with Sentry.Maui >=5.7.0-beta.0

[blazej-kosmowski]

Package

Sentry

.NET Flavor

.NET

.NET Version

9.0.303

OS

iOS

OS Version

iOS 17.x 18.6 18.5

Development Environment

Rider 2024 (MacOS)

SDK Version

5.7.0-beta0

Self-Hosted Sentry Version

No response

Workload Versions

maui 9.0.100

UseSentry or SentrySdk.Init call

public virtual void SetupSentry(SentryMauiOptions options)
{
    options.Dsn = "...";
    options.Debug = AppConstants.EnableDebugLog;
    options.Environment = AppConstants.Environment; 
    options.TracesSampleRate = AppConstants.EnableDebugLog
        ? TracesSampleRateDebug
        : TracesSampleRateProd;
    options.SendDefaultPii = true;
    options.SetBeforeSend(ev =>
    {
        ev.Contexts["YourApp"] = new
        {
            Version = GetAppVersion(),
            UserInfo = GetUserInfo()
        };
        // ... rest of logic
        return ev;
    });
}

Steps to Reproduce

1. Create a .NET MAUI iOS app.
2. Enable Sentry.
3. Add a CollectionView or repeatedly push/pop pages (navigation).
4. Run on iOS device or simulator.
5. After few iterations, app crashes.

Expected Result

No crash.
Breadcrumbs and lifecycle events should be recorded without accessing disposed UIView instances.

Actual Result

We got crash

System.ObjectDisposedException: Cannot access a disposed object.
Object name: '...Renderer'
   at UIKit.UIView.get_Window()
   at Microsoft.Maui.Platform.ViewExtensions.IsLoaded(UIView uiView)
   at Microsoft.Maui.Platform.ViewExtensions.<>c__DisplayClass59_0.<OnUnloaded>g__UnLoadedCheck|4()
   at Foundation.NSAsyncActionDispatcher.Apply()
   ...

Analysis

Sentry wires up MAUI event binders in SentryMauiAppBuilderExtensions.RegisterMauiEventsBinder.
These binders (e.g. MauiEventsBinder) subscribe to element events including Unloaded.
On iOS, MAUI’s ViewExtensions.OnUnloaded calls UIView.Window. If the native UIView has already been disposed, this throws ObjectDisposedException.
With Sentry enabled, the extra subscriptions increase the chance of hitting this race. Without Sentry, the app doesn’t crash.

This matches other recent iOS crash reports:
#4241: MAUI .NET 9 ObjectDisposedException disappears without Sentry
#4295: iOS crash during CollectionView virtualization (ObjectDisposedException)

Release 5.14.1 did not contain a fix for this path. The regression started in 5.7.0-beta.0, when auto-breadcrumbs were extended and binders were changed.

Regression info

Last known good: 5.6.0
First bad: 5.7.0-beta.0
Crash reproducible on all versions since then, including 5.14.1.

[linear]

NET-428 ObjectDisposedException when Unloaded triggers with Sentry.Maui >=5.7.0-beta.0

[jamescrosswell]

Hi @blazej-kosmowski, thanks for the report.

Could you provide the full stack trace, so that I can see where this is coming from in Sentry? I can't find any references in the codebase to UIView.Window or to any Unloaded event handlers... so not sure exactly which binder(s) this might be coming from.

[blazej-kosmowski]

Hi, thanks for looking into this.
Here’s the full stack trace we see on iOS (MAUI 9.0.100, Sentry.Maui 5.14.1):

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Temp.iOS.Renderers.SimpleLabelRenderer'.
   at ObjCRuntime.ThrowHelper.ThrowObjectDisposedException(Object o)
   at Foundation.NSObject.get_SuperHandle()
   at UIKit.UIView.get_Window()
   at Microsoft.Maui.Platform.ViewExtensions.IsLoaded(UIView uiView)
   at Microsoft.Maui.Platform.ViewExtensions.<>c__DisplayClass59_0.<OnUnloaded>g__UnLoadedCheck|4()
   at Foundation.NSAsyncActionDispatcher.Apply()
   --- End of stack trace from previous location ---
   at ObjCRuntime.Runtime.ThrowException(IntPtr gchandle)
   at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName)
   at UIKit.UIApplication.Main(String[] args, String principalClassName, String delegateClassName)
   at Temp.iOS.Application.Main(String[] args)

I understand Sentry doesn’t directly call UIView.Window. However, when UseSentry(...) is enabled, Sentry.Maui attaches MauiEventsBinder to MAUI element events (Loaded/Unloaded, BindingContextChanged, etc.).
On iOS, ViewExtensions.OnUnloaded internally calls IsLoaded -> UIView.Window, which throws if the native view has already been disposed.
With the extra subscriptions in place, Unloaded is triggered more frequently/asynchronously, increasing the chance of hitting this race. Without Sentry or before version 5.7.0-beta.0, I can’t reproduce the crash.

[jamescrosswell]

Hm, OK. @blazej-kosmowski as a temporary workaround (and to confirm that it's caused by Sentry's binders) you could call builder.Services.RemoveAll<IMauiElementEventBinder>(); after the call to UseSentry when initialising the application. This will disable Sentry's event binders.