dotnet publish fails with Mono assertion when using new InteractiveWebAssemblyRenderMode(prerender: false)

[Neth01]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

After modifying App.razor to use InteractiveWebAssemblyRenderMode on HeadOutlet and Routes, a published Blazor WebAssembly app (built with dotnet publish) fails at runtime with a Mono assertion:

[MONO] * Assertion at /__w/1/s/src/runtime/src/mono/mono/metadata/assembly.c:2718, condition `<disabled>' not met

Expected Behavior

The published WebAssembly app runs normally in the browser.

Steps To Reproduce

1. Create a new Blazor WebAssembly app:

dotnet new blazor --interactivity WebAssembly --all-interactive --no-https

2. Edit BlazorBug/Components/App.razor and change the HeadOutlet and Routes lines to:

<HeadOutlet @rendermode="new InteractiveWebAssemblyRenderMode(prerender: false)" />
...
<Routes @rendermode="new InteractiveWebAssemblyRenderMode(prerender: false)" />

3. Publish the app:

dotnet publish -c Release

4. Open the published app in a browser and check the developer console.

Exceptions (if any)

The browser console shows a Mono runtime assertion and the app fails to run. Example message:

dotnet.runtime.fn94ls2wwa.js:3  [MONO] * Assertion at /__w/1/s/src/runtime/src/mono/mono/metadata/assembly.c:2718, condition `<disabled>' not met

.NET Version

.NET SDK: 10.0.100-rc.2.25502.107 or .NET SDK: 9.0.306

Anything else?

• OS: Windows 11

Example project

BlazorBug.zip

[javiercn]

@Neth01 thanks for contacting us.

This looks like an issue that we experienced in the RC2 SDK. Can you try with the nightly RTM bits?

Potential dupe of #64049

[Neth01]

@javiercn Fixed in .NET SDK: 10.0.100