Generator 'RazorSourceGenerator' failed to generate source

[RobertOstermann]

Type: Bug

Issue Description

There is an error in the .csproj file in the new pre-release version of the extension.

Generator 'RazorSourceGenerator' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'FileNotFoundException' with message 'Could not load file or assembly 'Microsoft.AspNetCore.Razor.Utilities.Shared, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.
'.
System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.AspNetCore.Razor.Utilities.Shared, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.

File name: 'Microsoft.AspNetCore.Razor.Utilities.Shared, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'
at Microsoft.NET.Sdk.Razor.SourceGenerators.RazorSourceGenerator.<>c.b__6_19(HostOutputProductionContext context, ValueTuple2 pair) at Microsoft.CodeAnalysis.UserFunctionExtensions.<>c__DisplayClass3_02.b__0(TInput1 input1, TInput2 input2, CancellationToken token) in /_/src/Compilers/Core/Portable/SourceGeneration/UserFunction.cs:line 103

(CS8785)

Steps to Reproduce

Go to a .csproj file and the error is shown at the top.

Expected Behavior

No error

Actual Behavior

Error

Logs

C# log

Post the output from Output-->C# here

C# LSP Trace Logs

Post the output from Output-->C# LSP Trace Logs here. Requires the `C#` output window log level to be set to `Trace`

Environment information

VSCode version: 1.100.0-insider
C# Extension: 2.74.24
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 9.0.202 Commit: 3a53853c30 Workload version: 9.0.200-manifests.21502d11 MSBuild version: 17.13.13+1c2026462

Runtime Environment:
OS Name: Mac OS X
OS Version: 15.4
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/9.0.202/

.NET workloads installed:
There are no installed workloads to display.
Configured to use loose manifests when installing new manifests.

Host:
Version: 9.0.3
Architecture: arm64
Commit: 831d23e561

.NET SDKs installed:
8.0.404 [/usr/local/share/dotnet/sdk]
8.0.407 [/usr/local/share/dotnet/sdk]
9.0.202 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.6 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.11 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.14 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.3 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.6 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.11 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.14 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.3 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Visual Studio Code Extensions

Extension	Author	Version	Folder Name
csdevkit	ms-dotnettools	1.18.25	ms-dotnettools.csdevkit-1.18.25-darwin-arm64
csharp	ms-dotnettools	2.74.24	ms-dotnettools.csharp-2.74.24-darwin-arm64
dotnetwatchattach	Trottero	0.2.7	trottero.dotnetwatchattach-0.2.7
vscode-dotnet-runtime	ms-dotnettools	2.3.3	ms-dotnettools.vscode-dotnet-runtime-2.3.3

Extension version: 2.74.24
VS Code version: Code - Insiders 1.100.0-insider (1b000ef82b3c3082833f6b04e050bc0e4e12ae3b, 2025-04-18T05:31:28.011Z)
OS version: Darwin arm64 24.4.0
Modes:

System Info

Item	Value
CPUs	Apple M1 Max (10 x 2400)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	4, 4, 4
Memory (System)	64.00GB (2.62GB free)
Process Argv	--crash-reporter-id 428aa8ae-40f2-4aca-ab14-277ccfa15f06
Screen Reader	no
VM	0%

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[arunchndr]

Marked high-priority since this is showing fairly frequently in internal dogfooding as well. So a lot of pseudo upvotes that dont necessarily show here.