LeptonX ContentToolbar/Breadcrumbs never unsubscribe from PageLayout — async void handler terminates the host process (ObjectDisposedException #10861

5 Answer(s)

• 

  0

  AI-Bot created one month ago

  Support Team ABP Agent

  • Your analysis is correct: subscribing to a scoped PageLayout using anonymous async lambdas (effectively async void handlers for these events) and never unsubscribing can keep dead components alive and can also dispatch StateHasChanged() after the renderer/component scope is already disposed. In a Blazor Web App (InteractiveAuto), that race window is easier to hit, and an exception escaping an async void event handler can indeed become process-terminating.

  • Until there is an upstream fix in Volo.Abp.AspNetCore.Components.Web.LeptonXTheme, the safest application-level mitigation is exactly what you already did: replace the LeptonX theme components via DI and implement proper unsubscribe on dispose.

  Drop-in safe replacements (no markup changes)

  Create code-behind only subclasses (so you inherit the original generated markup) and replace the event hookups with named, non-async-void handlers + IDisposable.

  using System.Collections.Specialized;
  using System.ComponentModel;
  using Microsoft.AspNetCore.Components;
  using Volo.Abp.AspNetCore.Components.Web.LeptonXTheme.Components.ApplicationLayout.Common;
  
  public class MySafeContentToolbar : ContentToolbar, IDisposable
  {
      private NotifyCollectionChangedEventHandler? _toolbarItemsChanged;
      private PropertyChangedEventHandler? _pageLayoutPropertyChanged;
  
      protected override Task OnInitializedAsync()
      {
          _toolbarItemsChanged = ToolbarItemsChanged;
          _pageLayoutPropertyChanged = PageLayoutPropertyChanged;
  
          PageLayout.ToolbarItems.CollectionChanged += _toolbarItemsChanged;
          PageLayout.PropertyChanged += _pageLayoutPropertyChanged;
  
          // IMPORTANT: do NOT call base.OnInitializedAsync() (it attaches the anonymous handlers)
          return Task.CompletedTask;
      }
  
      private void ToolbarItemsChanged(object? sender, NotifyCollectionChangedEventArgs e)
          => _ = InvokeAsync(RenderAsync); // observe on renderer sync context
  
      private void PageLayoutPropertyChanged(object? sender, PropertyChangedEventArgs e)
          => _ = InvokeAsync(StateHasChanged);
  
      public void Dispose()
      {
          if (_toolbarItemsChanged != null)
          {
              PageLayout.ToolbarItems.CollectionChanged -= _toolbarItemsChanged;
          }
          if (_pageLayoutPropertyChanged != null)
          {
              PageLayout.PropertyChanged -= _pageLayoutPropertyChanged;
          }
      }
  }
  

  using System.Collections.Specialized;
  using System.ComponentModel;
  using Microsoft.AspNetCore.Components;
  using Volo.Abp.AspNetCore.Components.Web.LeptonXTheme.Components.ApplicationLayout.Common;
  
  public class MySafeBreadcrumbs : Breadcrumbs, IDisposable
  {
      private NotifyCollectionChangedEventHandler? _breadcrumbItemsChanged;
      private PropertyChangedEventHandler? _pageLayoutPropertyChanged;
  
      protected override Task OnInitializedAsync()
      {
          _breadcrumbItemsChanged = BreadcrumbItemsChanged;
          _pageLayoutPropertyChanged = PageLayoutPropertyChanged;
  
          PageLayout.BreadcrumbItems.CollectionChanged += _breadcrumbItemsChanged;
          PageLayout.PropertyChanged += _pageLayoutPropertyChanged;
  
          // IMPORTANT: do NOT call base.OnInitializedAsync()
          return Task.CompletedTask;
      }
  
      private void BreadcrumbItemsChanged(object? sender, NotifyCollectionChangedEventArgs e)
          => _ = InvokeAsync(StateHasChanged);
  
      private void PageLayoutPropertyChanged(object? sender, PropertyChangedEventArgs e)
          => _ = InvokeAsync(StateHasChanged);
  
      public void Dispose()
      {
          if (_breadcrumbItemsChanged != null)
          {
              PageLayout.BreadcrumbItems.CollectionChanged -= _breadcrumbItemsChanged;
          }
          if (_pageLayoutPropertyChanged != null)
          {
              PageLayout.PropertyChanged -= _pageLayoutPropertyChanged;
          }
      }
  }
  

  Register replacements (as you noted, for Blazor Web App do it in both Server and .Client modules where the layout can render):

  using Microsoft.Extensions.DependencyInjection;
  using Microsoft.Extensions.DependencyInjection.Extensions;
  using Volo.Abp.AspNetCore.Components.Web.LeptonXTheme.Components.ApplicationLayout.Common;
  
  context.Services.Replace(ServiceDescriptor.Transient<ContentToolbar, MySafeContentToolbar>());
  context.Services.Replace(ServiceDescriptor.Transient<Breadcrumbs, MySafeBreadcrumbs>());
  

  Why this mitigates the host crash

  • No anonymous handlers → you can unsubscribe reliably.
  • No async void propagation → work is scheduled via InvokeAsync(...) and exceptions are observed by the renderer pipeline rather than surfacing as unhandled ThreadPool exceptions.
  • Dispose() ensures dead components stop receiving layout notifications, preventing renders against disposed Autofac scopes.

  Relevant official docs (how to replace LeptonX components / how PageLayout works)

  • https://abp.io/docs/10.6/ui-themes/lepton-x/blazor?UI=BlazorServer&BlazorUI=MudBlazor
  • https://abp.io/docs/10.6/framework/ui/blazor/page-layout?BlazorUI=Blazorise

  If you want this fixed upstream in the theme package, please report it through the official channel so it can be tracked and patched: https://abp.io/contact

  ---

  This response was generated by AI. If it didn’t solve your problem, feel free to post a new answer — our support team will jump in to help you soon.

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• 

  0

  RedEnzian created one month ago

  Second part of the Bugreport (related issue but located in ABP source instead of LeptonX) can be found here: https://github.com/abpframework/abp/issues/26075

  Iam not sure if this is the correct place for a LeptonX Bugreport or if i should open a bug issue on github abpframework/abp issue page.

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• 

  0

  maliming created one month ago

  Support Team Fullstack Developer

  hi

  I will check this case.

  Thanks.

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• 

  0

  maliming created one month ago

  Support Team Fullstack Developer

  Hi,

  ContentToolbar and Breadcrumbs subscribe to the scoped PageLayout with anonymous async handlers and never remove them, so a layout notification can still reach a component the renderer has already discarded. This will be fixed in LeptonX 5.7.0.

  Until then, replace both components with subclasses that keep the handlers in fields and unsubscribe on dispose:

  using System;
  using System.Collections.Specialized;
  using System.ComponentModel;
  using System.Threading.Tasks;
  using Volo.Abp.AspNetCore.Components.Web.LeptonXTheme.Components.ApplicationLayout.Common;
  
  namespace MyProject.Blazor.Client.Theming;
  
  public class SafeContentToolbar : ContentToolbar, IDisposable
  {
      private bool _disposed;
  
      protected override Task OnInitializedAsync()
      {
          // Not calling base, it attaches the anonymous handlers.
          PageLayout.ToolbarItems.CollectionChanged += OnToolbarItemsCollectionChanged;
          PageLayout.PropertyChanged += OnPageLayoutPropertyChanged;
          return Task.CompletedTask;
      }
  
      private async void OnToolbarItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
      {
          if (_disposed)
          {
              return;
          }
  
          try
          {
              await RenderAsync();
          }
          catch (ObjectDisposedException)
          {
          }
      }
  
      private async void OnPageLayoutPropertyChanged(object sender, PropertyChangedEventArgs e)
      {
          if (_disposed)
          {
              return;
          }
  
          try
          {
              await InvokeAsync(StateHasChanged);
          }
          catch (ObjectDisposedException)
          {
          }
      }
  
      public void Dispose()
      {
          _disposed = true;
          PageLayout.ToolbarItems.CollectionChanged -= OnToolbarItemsCollectionChanged;
          PageLayout.PropertyChanged -= OnPageLayoutPropertyChanged;
      }
  }
  

  SafeBreadcrumbs : Breadcrumbs is the same shape, subscribing to PageLayout.BreadcrumbItems.CollectionChanged instead, with await InvokeAsync(StateHasChanged) in both handlers.

  Register them in the ConfigureServices of both your .Blazor and .Blazor.Client modules:

  using Microsoft.Extensions.DependencyInjection.Extensions;
  using Volo.Abp.AspNetCore.Components.Web.LeptonXTheme.Components.ApplicationLayout.Common;
  
  context.Services.Replace(ServiceDescriptor.Transient<ContentToolbar, SafeContentToolbar>());
  context.Services.Replace(ServiceDescriptor.Transient<Breadcrumbs, SafeBreadcrumbs>());
  

  You can drop both classes and the registrations once you upgrade to 5.7.0.

  The support ticket is the right place for LeptonX, the theme packages are not in the abpframework/abp repository. The framework side you opened at https://github.com/abpframework/abp/issues/26075 is tracked there.

  Thanks

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• 

  0

  maliming created one month ago

  Support Team Fullstack Developer

  Hi,

  The layout components now unsubscribe from PageLayout when they are disposed, so a notification raised while the page is being torn down can no longer reach a discarded component. This is in for LeptonX 5.7.0.

  Your ticket has been refunded.

  Thanks

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