[Blazor] Creating Interactive WebAssembly or Auto apps with Container Support triggers missing launchSettings.json error popup

[BharatRamsf3693]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When creating a Blazor Web App with Interactive WebAssembly or Interactive Auto render modes and Container Support enabled, Visual Studio displays an unexpected file path error popup during project creation.

The popup reports that it cannot find the launchSettings.json file in the generated Client project. Although the project is successfully created after dismissing the popup, the error interrupts the project creation experience and may lead users to believe that project creation has failed.

Expected Behavior

The project should be created successfully without displaying any error popups when Container Support is enabled.

Steps To Reproduce

1. Open Visual Studio 2026 Insiders [12023.133] Professional.
2. Create a new Blazor Web App.
3. Choose either:

• Interactive WebAssembly
• Interactive Auto

4. Enable Container Support.
5. Select Create.
6. Observe the following popup error:
   Could not find a part of the path "...\<ProjectName>.Client\Properties\launchSettings.json"

Interactivity WebAsssembly:

Interactive Auto:

7. Select OK to dismiss the popup.
8. Project creation completes successfully.

Exceptions (if any)

Could not find a part of the path "...<ProjectName>.Client\Properties\launchSettings.json"

.NET Version

11.0.100-preview.7.26381.103

Anything else?

Visual Studio: VS 2026 Insiders [12023.133] Professional
OS: Windows 11 Enterprise
Evidence: https://github.com/BharatRamsf3693/BlazorWebApp-ContainerSupport-Validation/blob/main/Evidence/ContainerSupport-On-CreationDialog/blazor-creation-dialog.zip

[github-actions]

Triage Summary

Area: area-blazor (issue concerns Blazor Web App project template creation with Interactive WebAssembly/Auto render modes and IDE Container Support)
Type: Bug (reproducible error popup during project creation, with clear repro steps and screenshots)

Potential Duplicates

• [Validation] Enabling container support when creating a Blazor Web App #68543 - [Validation] Enabling container support when creating a Blazor Web App (related validation scenario for the same feature area, not the same reported symptom)

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