Last Updated: 08 Sep 2020 12:21 by ADMIN
Release 2.17.0
Created on: 13 Mar 2020 15:26
Category: NumericTextBox
Type: Bug Report
System.Threading.Tasks.TaskCanceledException: A task was canceled after the component is disposed

I am getting the following Exception when I:

  • Navigate to a page that has a component that uses NumericTextBox.
  • Hit refresh (F5)
  • Wait for about 60 seconds while leaving the page idle

Trace stack of the error:


fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
      Unhandled exception in circuit 'pPIYHdNTGKpuLp_f48NvOZyLpp6b2uJIdLYu2ndwIlc'.
System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at Microsoft.JSInterop.JSRuntime.InvokeWithDefaultCancellation[T](String identifier, Object[] args)
   at Telerik.Blazor.Components.TelerikNumericTextBoxBase`1.Dispose()
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__139_0(Object state)
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.ExecuteSynchronously(TaskCompletionSource`1 completion, SendOrPostCallback d, Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.ExecuteBackground(WorkItem item)


Posted on: 20 Apr 2020 15:53
Was able to repo the issue and save into GitHub.  Mine turned out to be caused MS Identity, upgrading from 3.1.1 packages to 3.1.3 packages.  Will file a ticket.
Marin Bratanov
Posted on: 20 Apr 2020 11:47

Hi Brian,

We are aware of a similar issue that stems from the lack of a proper OnUnmount event in Blazor, you can read more about this here: Is your case the same? If not, please post the new issue either in a new public thread, or in a private ticket, so I can have a look.


Marin Bratanov
Progress Telerik

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Posted on: 20 Apr 2020 04:15

I'm getting a similar exception now.  I've traced it to the opening and closing of TelerikWindow.  Correct, it does not break the application.  But, it was not there in 2.9.  Something has changed.  Spent the last 2 hours chasing this down, suspecting something in MY code was broken.  Damned annoying.  I might be able to do a simplified example if needed.

Svetoslav Dimitrov
Posted on: 13 Mar 2020 17:03


This behavior can be observed in the Debug Output in Visual Studio and does not break the application.

Svetoslav Dimitrov
Progress Telerik

 UI for Blazor