Navigating away while a Web Worker operation is running can sometimes cause an unhandled error in the browser console.

[Vinoth2562000]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

What Happened

In the Blazor WebAssembly standalone and Interactive WebAssembly sample, clicking Run in Worker starts a 5-second worker operation. If you navigate from Counter to Weather before the operation finishes and then return to Counter, an error may appear in the browser console. This issue occurs randomly and is not consistently reproducible.

Expected Behavior

When navigating away, the WebWorkerClient should be disposed or cancelled safely. Any running worker operation should complete, cancel, or fail gracefully without causing unhandled browser or Blazor errors. Returning to the Counter page should create a clean component instance.

Steps To Reproduce

1. Install .NET SDK 11.0.100-preview.7.26381.103
2. Clone the sample repository:
   https://github.com/Vinoth2562000/BlazorWebWorkerValidation/tree/main/Standalone_WebAssembly_NET11
3. Open a terminal and navigate to the BlazorWebWorkerStandalone project folder.
4. Install the dotnet-serve tool (if it is not already installed):

dotnet tool install --global dotnet-serve

5. Publish the application:

dotnet publish -c Release

6. Navigate to the publish output directory:

cd bin\Release\net11.0\publish\wwwroot

7. Host the published application:

dotnet-serve -S

8. Open the localhost URL displayed in the terminal.
9. Open the Counter page.
10. Click Run in Worker.
11. Before the 5-second operation completes, navigate to the Weather page.
12. Navigate back to the Counter page.
13. Click anywhere on the page and wait for the original worker operation to complete.
14. Open Browser DevTools → Console and check for unhandled errors.
15. Repeat the steps multiple times, as the issue occurs intermittently.

Evidence

• ClientDisposalAndNavigationValidation_Fail.mp4

Error Logs

• Contains error log documents

Published Files

• Contains published file documents

Screenshot

Observed Behavior

Disposing the WebWorkerClient and navigating away while a worker operation is still running can sometimes result in an unhandled browser console error.

Exceptions (if any)

No response

.NET Version

.NET SDK 11.0.100-preview.7.26381.103

Anything else?

No response

[github-actions]

Triage Summary

Area: area-blazor (issue involves WebWorkerClient, Blazor WebAssembly standalone/Interactive WebAssembly navigation and component disposal)
Type: Bug (preserved)

Potential Duplicates

• [Validation] Cancellation and timeouts on WebWorkerClient calls #68819 - [Validation] Cancellation and timeouts on WebWorkerClient calls (similarity: medium) — a validation-scenario issue covering cancellation/timeout/disposal of WebWorkerClient and requiring "no unhandled error ... during any cancellation, timeout or disposal," closely related to this report but framed as a validation task rather than a bug report.

Notes

• Missing: exact browser console error/exception text and full stack trace (referenced log file is external and not inlined in the issue body).

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