[Blazor] Creating Interactive WebAssembly or Auto apps with Container Support triggers missing launchSettings.json error popup
- Dominant language
- C#
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Description
### Is there an existing issue for this?
- [x] 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
"...\.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 "...\.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
Contributor guide
Research direction
Reproduce project creation for Interactive WebAssembly and Interactive Auto with Container Support enabled, then inspect the generated .Client/Properties/launchSettings.json path mentioned in the error. Compare the generated project with and without Container Support and verify that creation completes without a missing-file popup in both render modes.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp, docker, wasm
- Domain
- devops, frontend, tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100