dotnet / dotnet/runtime

WasmFingerprintAssets false breaks type/value information in WASM debugging

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#122,201 7 comments 0 reactions 2 assignees Claimed by @kotlarmilos View on GitHub
arch-wasm area-Debugger-mono os-browser
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C#
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Description

### Description

I have found that the build property `WasmFingerprintAssets` has been the cause of my severely impaired debugging experience on a WASM Browser App (SDK `Microsoft.NET.Sdk.WebAssembly`).

Stepping works somehow, control flow etc reflects fine, but anything related to types or locals is showing the error below. I have not been able to find any sensible logging explaining why, I managed to find this by stripping my solution down step by step.

Image

The browser console contains the following message, a couple dozen times.

Image

### Reproduction Steps

A minimal repro that i verified on a sample project:

1. Download the [WASMBrowserAppImportExportInterop sample project](https://github.com/dotnet/blazor-samples/tree/main/10.0/WASMBrowserAppImportExportInterop)
3. Add `false` to the `.csproj`
4. Rebuild
5. Launch a debugging session from Visual Studio (I used 2026)

### Expected behavior

The debugging experience remains the same with or without the WasmFingerprintAssets property set.

### Actual behavior

Locals and type information is not available during debugging. Stepping still works.
Anything like a (quick)watch of local inspection attempt results in the message `Internal error in the C# compiler`.

### Regression?

-

### Known Workarounds

Keep `WasmFingerprintAssets` set to `true` resolves the debugging issues.

### Configuration

Built with the latest .NET 10.0.100 SDK bundle. Running on the Mono wasm runtime.
Windows 10/11 same problem.

I presume this is not specific to my machine configuration.

Its happened in Chrome 142.0.7444.176

### Other information

_No response_

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