Emcc build error after upgrading Blazor Wasm app to .NET 10 #121843

This issue has been moved from a ticket on Developer Community.

[severity:I'm unable to use this version] [regression] [worked-in:Insiders 11218.70]
I have a blazor wasm app which works fine in .NET 9 but does not build in .NET 10. I get the below 2 errors:

The command "emcc "@C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Runtime.Mono.browser-wasm\10.0.0\runtimes\browser-wasm\native\src\emcc-default.rsp" -msimd128 "@C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Runtime.Mono.browser-wasm\10.0.0\runtimes\browser-wasm\native\src\emcc-link.rsp" "@C:\Ws\Repo\DEV\PDS\NetCore\Client\PDS. Web\Site\obj\Debug\net10.0\wasm\for-build\emcc-link.rsp"" exited with code 1.

/NODEFAULTLIB:MSVCRT: No such file or directory ("/NODEFAULTLIB:MSVCRT" was expected to be an input file, based on the commandline arguments provided)

When I double click the error it takes me to BrowserWasmApp.targets line 522:

    <Exec Command='emcc "@$(_WasmDefaultFlagsRsp)" $(_WasmDefaultFlags) "@$(_WasmDefaultLinkFlagsRsp)" "@$(_WasmLinkRsp)"' EnvironmentVariables="@(EmscriptenEnvVars)" ConsoleToMSBuild="true">
      <Output TaskParameter="ConsoleOutput" PropertyName="_EmccLinkStepConsoleOutput" />
      <Output TaskParameter="ExitCode" PropertyName="_EmccLinkStepExitCode" />
    </Exec>

Completely unable to proceed as a result.

Original Comments

Feedback Bot on 11/20/2025, 03:40 AM:

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Original Solutions

William Buchanan solved on 11/20/2025, 06:16 AM, undefined votes:

I have an update on this. Problem wasn’t happening on another developer’s PC. The difference we noticed was that he hadn’t installed the .NET 10 Runtime whereas I had. I uninstalled VS and everything .NET 10 related. The folder with the targets file still existed (C:\Program Files\dotnet\packs\Microsoft.NET.Runtime.WebAssembly.Sdk\10.0.0) so I renamed this folder. Rebooted and reinstalled VS2026 without installing other .NET packages and now the problem has gone.