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This repository was archived by the owner on Dec 26, 2025. It is now read-only.
This repository was archived by the owner on Dec 26, 2025. It is now read-only.

[Bug] Toasts not shown when using IToastService from a DelegatingHandler in Blazor WASM #272

Description

@Noveboi

Describe the bug
When invoking any IToastService.ShowXYZ method from a DelegatingHandler in a Blazor WebAssembly environment, the result is that no toast is shown in the UI.

To Reproduce
Steps to reproduce the behavior:

  1. Clone the minimal repro repository: https://github.com/Noveboi/BlazoredToastDelegatingHandlers
  2. Run the app
  3. Click the "Show Toast" button to ensure that toasts are shown in a regular scenario
  4. Click the "Call HttpClient" button to see that no toasts are shown
  5. Open browser console to find the log that shows the DelegatingHandler is actually being invoked.
Image

Expected behavior
Two info toasts should appear, one when the request is sent and one when the response is received. Take a look at the DelegatingHandler's code to see exactly what should happen:

internal sealed class HttpNotificationMiddleware(
    IToastService toast,
    ILogger<HttpNotificationMiddleware> log) : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        log.LogInformation("To verify the handler is actually being run!");
        toast.ShowInfo("Sending request!");
        
        var response = await base.SendAsync(request, cancellationToken);
        
        toast.ShowInfo("Got response!");
        return response;
    }
}

Hosting Model (is this issue happening with a certain hosting model?):
Blazor WebAssembly

Additional context
I will post comments if I find anything useful

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