Standalone Blazor WebAssembly app log output is very verbose on .NET 11 Preview 5

[danroth27]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When I create a new standalone Blazor WebAssembly app on .NET 11 Preview 5 (dotnet new blazorwasm) and run it (dotnet run / dotnet watch / F5 in Visual Studio), the console produces a very large volume of log output compared to the same scenario on .NET 10. A single app load emits multiple Information-level lines per HTTP request through the Microsoft.AspNetCore.Hosting.Diagnostics, Microsoft.AspNetCore.Routing.EndpointMiddleware, and Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker categories. Because a Blazor WebAssembly boot pulls many assets, this results in hundreds of log lines for a single page load.

The equivalent standalone Blazor WebAssembly app on .NET 10 starts up with only a handful of log lines and stays quiet during normal browsing.

Expected Behavior

A freshly created standalone Blazor WebAssembly app should have a console log volume comparable to the .NET 10 experience — roughly: startup banner, listening URL, hosting environment, content root, and not much else during normal dev-time browsing.

Steps To Reproduce

1. Install the .NET 11 Preview 5 SDK (11.0.100-preview.5.26272.118).
2. dotnet new blazorwasm -o WasmTest
3. cd WasmTest
4. dotnet run
5. Open http://localhost:<port>/ in a browser.
6. Observe the console output.

Per-request output (one example request, repeated for every asset):

info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:5000/ - - -
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint ''Microsoft.AspNetCore.Routing.RouteEndpoint''
info: Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker[2]
      Sending file. Request path: ''{**fallback:nonfile}''. Physical path: ''...\obj\Debug\net11.0\compressed\...gz''
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint ''Microsoft.AspNetCore.Routing.RouteEndpoint''
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 GET http://localhost:5000/ - 200 1376 text/html 302.9165ms

Exceptions (if any)

None.

.NET Version

11.0.100-preview.5.26272.118

Anything else?

• OS: Windows 11
• Template: dotnet new blazorwasm (standalone)
• Reproduces with dotnet run, dotnet watch, and Visual Studio Insiders F5
• Same template on .NET 10 (net10.0) is significantly quieter

[github-actions]

Triage Summary

Area: area-blazor (already labeled — involves standalone Blazor WebAssembly app template behavior and its dev-time console logging)
Type: Bug — The app produces far more log output than expected/intended in .NET 11 compared to .NET 10, which is a regression in behavior.

Regression Info

• Previously working version: .NET 10
• Broken since: .NET 11 (11.0.100-preview.5.26272.118)
• On .NET 10, a standalone Blazor WebAssembly app emits only a handful of startup log lines during normal dev-time browsing. On .NET 11 Preview 5, every HTTP request (and a Blazor WASM boot fetches many assets) emits multiple Information-level lines from Microsoft.AspNetCore.Hosting.Diagnostics, Microsoft.AspNetCore.Routing.EndpointMiddleware, and Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker, resulting in hundreds of log lines per page load.

Potential Duplicates

• None found — searches for "blazor wasm verbose logging" and "StaticAssetsInvoker logging console output" did not surface matching open issues.

Notes

• The noisiness is likely caused by a change in the default log level configuration or a new logging call added to StaticAssetsInvoker (or related middleware) that was not present/not at Information level in .NET 10. Adjusting the default appsettings.Development.json log filter for the relevant categories in the Blazor WASM template (or changing the log level of those messages) would likely fix the regression.
• The Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker category is a strong signal — this area did not exist in .NET 10 and may have introduced new Information-level logging that should be Debug or lower in the default template configuration.

Generated by Issue Triage Agent for dotnet/aspnetcore for issue #66879 · sonnet46 678.7K · ◷