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Blazor app returns 404 for _framework/dotnet-browser-tools/hot-reload-settings.json after installing 11.0 RTM #69718

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Blazor app returns 404 for _framework/dotnet-browser-tools/hot-reload-settings.json after installing 11.0 RTM#69718
Bug
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VigneshwaranGovindharajan
Labels
Regressionarea-blazorIncludes: Blazor, Razor Components
Milestone
Backlog

Description

@jinzhao1127
jinzhao1127
opened on Oct 8, 2026

REGRESSION INFO: Not reproduces after installing 11.0-RC 1, reproduces after installing 11.0-RC 2

INSTALL STEPS:

  1. Clean Win 11 25h2 x64
  2. Install latest 11.0 RTM daily build
  3. Install 10.0.401 SDK
  4. Apply Feed

Platform

  • Windows
  • macOS
  • Linux

Repro Steps

  1. Open up a normal Command Prompt (Terminal)

  2. Create a 10.0 Blazor Web Server project and run it.

    dotnet new blazor -o Server -f net10.0
cd Server
dotnet run

  3. Open the URL on the browser

  4. F12 to open the develop console window

Note:

  1. Not reproduces on net11 project, reproduces on 10.0/9.0/8.0 after installing net11
  2. Also reproduces on Blazor Server/WebAssembly/Auto and Blazor WASM Standalone app
  3. Also reproduces when running the project in VS

Actual Result
There is an error "Microsoft.NET.Sdk.We…c.lib.module.js:101 GET http://localhost:5249/_framework/dotnet-browser-tools/hot-reload-settings.json 404 (Not Found)"

Image

Activity

  1. github-actions commented on Oct 8, 2026

    @github-actions
    github-actionsbot
    on Oct 8, 2026 – with GitHub Actions
    Contributor

    Triage Summary

    Area: area-blazor (Blazor Web App / WebAssembly projects requesting _framework/dotnet-browser-tools/hot-reload-settings.json)
    Type: Bug (404 error in the browser console for a default Blazor template)

    Regression Info

    • Previously working version: 11.0 RC 1 (per reporter, not reproduced)
    • Failing version: 11.0 RC 2 (per reporter, reproduces with net10.0/9.0/8.0 Blazor projects; not net11 projects)
    • Reporter states the 404 console error appears for older-TFM Blazor projects only after the newer build is installed.

    Potential Duplicates

    • None found

    Generated by Issue Triage Agent for dotnet/aspnetcore for #69718 · copilot · auto · 25.9 AIC · ⌖ 0.997 AIC · ⊞ 30.4K · ◷

  2. github-actions
    added the
    Bug
    issue type on Oct 8, 2026
  3. github-actions
    added
    area-blazorIncludes: Blazor, Razor Components
    Regression
    on Oct 8, 2026
  4. saravanangn
    assigned
    VigneshwaranGovindharajan
    on Oct 8, 2026

  5. jinzhao1127 commented on Oct 8, 2026

    @jinzhao1127
    jinzhao1127
    on Oct 8, 2026
    Author

    This issue seems that related with #69390 @javiercn could you have a look?

  6. oroztocil commented on Oct 8, 2026

    @oroztocil
    oroztocil
    on Oct 8, 2026
    Member

    @jinzhao1127 Can you provide the dotnet --info output captured from the affected project directory and the exact .NET 11 daily build version?

  7. oroztocil
    added this to the Backlog milestone on Oct 8, 2026

  8. jinzhao1127 commented on Oct 9, 2026

    @jinzhao1127
    jinzhao1127
    on Oct 9, 2026
    Author

    @jinzhao1127 Can you provide the dotnet --info output captured from the affected project directory and the exact .NET 11 daily build version?

    @oroztocil dotnet --info output captured from the affected project directory as below image, exact .NET 11 daily build version is 11.0.100-rtm.26480.113
    Image

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