C# Extension creates build artifacts in source tree

[TheMemorius]

Type: Bug

Issue Description

Since the last VS Code update to 1.104.0, the editor suddenly creates bin/ and obj/ folders in several places in my source tree.

├───bin
│   └───Debug
│       └───net10.0
└───obj
    └───Debug
        └───net10.0
            │   .NETCoreApp,Version=v10.0.AssemblyAttributes.cs
            │   WorldManager.AssemblyInfo.cs
            │   WorldManager.AssemblyInfoInputs.cache
            │   WorldManager.GeneratedMSBuildEditorConfig.editorconfig
            │   WorldManager.GlobalUsings.g.cs
            │
            ├───ref
            └───refint

I narrowed it down to the C# extension. As soon as I enable that, these folders get created.

Steps to Reproduce

• Open a C# project (in my case a Unity project)
• Enable the C# extension if it isn't already enabled

Expected Behavior

No files or directories created in the source tree.

Actual Behavior

bin/ and obj/ directories are created.

Extension version: 2.90.60
VS Code version: Code 1.104.0 (f220831ea2d946c0dcb0f3eaa480eb435a2c1260, 2025-09-10T06:46:18.035Z)
OS version: Windows_NT x64 10.0.26100
Modes:

Logs

C# log

2025-09-14 16:52:34.956 [info] Locating .NET runtime version 9.0.1
2025-09-14 16:52:35.352 [info] Did not find .NET 9.0.1 on path, falling back to acquire runtime via ms-dotnettools.vscode-dotnet-runtime
2025-09-14 16:52:35.539 [info] Dotnet path: c:\Users\svenh\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\9.0.9~x64~aspnetcore\dotnet.exe
2025-09-14 16:52:35.539 [info] Activating C# + C# Dev Kit...
2025-09-14 16:52:35.693 [info] [stdout] info: Program[0]
      Server started with process ID 26696

2025-09-14 16:52:37.194 [info] [stdout] {"pipeName":"\\\\.\\pipe\\dde26822"}

2025-09-14 16:52:37.194 [info] received named pipe information from server
2025-09-14 16:52:37.194 [info] client has connected to server
2025-09-14 16:52:37.303 [info] [Program] Language server initialized
2025-09-14 16:52:38.195 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.DotnetCliHelper] Using dotnet executable configured on the PATH
2025-09-14 16:52:38.423 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:52:38.429 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:52:38.732 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\svenh\.vscode\extensions\ms-dotnettools.csharp-2.90.60-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-09-14 16:52:39.508 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\GenesisEditors.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.540 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\Tests.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.544 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\GenesisUtils.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.546 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\Genesis.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.582 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\GenesisPostProcessing.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.593 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\Assembly-CSharp.csproj loaded by C# Dev Kit
2025-09-14 16:52:39.649 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Dev\Genesis\NoSingletonsTestASM.csproj loaded by C# Dev Kit
2025-09-14 16:52:40.193 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Completed (re)load of all projects in 00:00:02.0159934
2025-09-14 16:54:05.502 [info] Locating .NET runtime version 9.0.1
2025-09-14 16:54:05.807 [info] Did not find .NET 9.0.1 on path, falling back to acquire runtime via ms-dotnettools.vscode-dotnet-runtime
2025-09-14 16:54:05.977 [info] Dotnet path: c:\Users\svenh\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\9.0.9~x64\dotnet.exe
2025-09-14 16:54:05.977 [info] Activating C# standalone...
2025-09-14 16:54:06.084 [info] [stdout] info: Program[0]
      Server started with process ID 8596

2025-09-14 16:54:07.058 [info] [stdout] {"pipeName":"\\\\.\\pipe\\48d7449b"}

2025-09-14 16:54:07.059 [info] received named pipe information from server
2025-09-14 16:54:07.059 [info] client has connected to server
2025-09-14 16:54:07.140 [info] [Program] Language server initialized
2025-09-14 16:54:07.477 [info] [solution/open] [LanguageServerProjectSystem] Loading d:\Dev\Genesis\Genesis.sln...
2025-09-14 16:54:07.820 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.DotnetCliHelper] Using dotnet executable configured on the PATH
2025-09-14 16:54:07.974 [info] [solution/open] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\svenh\.vscode\extensions\ms-dotnettools.csharp-2.90.60-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-09-14 16:54:07.976 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:54:08.027 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:54:08.031 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:54:08.287 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\svenh\.vscode\extensions\ms-dotnettools.csharp-2.90.60-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-09-14 16:54:09.505 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.csproj has unresolved dependencies
2025-09-14 16:54:09.528 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.cs
2025-09-14 16:54:09.529 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.csproj has unresolved dependencies
2025-09-14 16:54:09.530 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.cs
2025-09-14 16:54:09.532 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.csproj has unresolved dependencies
2025-09-14 16:54:09.532 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.cs
2025-09-14 16:54:10.327 [error] [workspace/_roslyn_restore] [Microsoft.CodeAnalysis.LanguageServer.Handler.RestoreHandler] Restore completed with errors.
2025-09-14 16:54:10.329 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Completed (re)load of all projects in 00:00:02.5548781
2025-09-14 16:54:10.829 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Tests.csproj
2025-09-14 16:54:11.174 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Genesis.csproj
2025-09-14 16:54:11.779 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\GenesisPostProcessing.csproj
2025-09-14 16:56:39.881 [info] Locating .NET runtime version 9.0.1
2025-09-14 16:56:40.192 [info] Did not find .NET 9.0.1 on path, falling back to acquire runtime via ms-dotnettools.vscode-dotnet-runtime
2025-09-14 16:56:40.387 [info] Dotnet path: c:\Users\svenh\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\9.0.9~x64\dotnet.exe
2025-09-14 16:56:40.388 [info] Activating C# standalone...
2025-09-14 16:56:40.488 [info] [stdout] info: Program[0]
      Server started with process ID 25492

2025-09-14 16:56:41.456 [info] [stdout] {"pipeName":"\\\\.\\pipe\\d6086a8b"}

2025-09-14 16:56:41.456 [info] received named pipe information from server
2025-09-14 16:56:41.456 [info] client has connected to server
2025-09-14 16:56:41.534 [info] [Program] Language server initialized
2025-09-14 16:56:41.873 [info] [solution/open] [LanguageServerProjectSystem] Loading d:\Dev\Genesis\Genesis.sln...
2025-09-14 16:56:42.203 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.DotnetCliHelper] Using dotnet executable configured on the PATH
2025-09-14 16:56:42.376 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:56:42.376 [info] [solution/open] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\svenh\.vscode\extensions\ms-dotnettools.csharp-2.90.60-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-09-14 16:56:42.408 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:56:42.417 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for 'd:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-09-14 16:56:42.661 [info] [textDocument/documentSymbol] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from c:\Users\svenh\.vscode\extensions\ms-dotnettools.csharp-2.90.60-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe reloading to start from C:\Program Files\dotnet\dotnet.exe to match necessary SDK location.
2025-09-14 16:56:43.884 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.csproj has unresolved dependencies
2025-09-14 16:56:43.955 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Chunking\WorldManager.cs
2025-09-14 16:56:43.956 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.csproj has unresolved dependencies
2025-09-14 16:56:43.956 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Tests\MockSaveManager.cs
2025-09-14 16:56:43.957 [warning] [textDocument/documentSymbol] [LanguageServerProjectLoader] Project d:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.csproj has unresolved dependencies
2025-09-14 16:56:43.958 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assets\Scripts\Tests\ChunkMapTest.cs
2025-09-14 16:56:44.814 [error] [workspace/_roslyn_restore] [Microsoft.CodeAnalysis.LanguageServer.Handler.RestoreHandler] Restore completed with errors.
2025-09-14 16:56:44.816 [info] [textDocument/documentSymbol] [LanguageServerProjectLoader] Completed (re)load of all projects in 00:00:02.6585938
2025-09-14 16:56:45.300 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Assembly-CSharp.csproj
2025-09-14 16:56:45.550 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Genesis.csproj
2025-09-14 16:56:46.196 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\GenesisUtils.csproj
2025-09-14 16:56:47.428 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\GenesisEditors.csproj
2025-09-14 16:56:47.507 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\NoSingletonsTestASM.csproj
2025-09-14 16:56:48.093 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\Tests.csproj
2025-09-14 16:56:48.708 [info] [solution/open] [LanguageServerProjectLoader] Successfully completed load of d:\Dev\Genesis\GenesisPostProcessing.csproj
2025-09-14 16:56:48.708 [info] [solution/open] [LanguageServerProjectLoader] Completed (re)load of all projects in 00:00:06.6737490

C# LSP Trace Logs log

Environment Information

VSCode version: 1.104.0
C# Extension: 2.90.60
Using OmniSharp: false

Dotnet Information

Host:
Version: 9.0.9
Architecture: x64
Commit: 893c2ebbd4
RID: win-x64

.NET SDKs installed:
No SDKs were found.

.NET runtimes installed:
Microsoft.NETCore.App 9.0.9 [c:\Users\svenh\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime.dotnet\9.0.9~x64\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
cmake	twxs	0.0.17	twxs.cmake-0.0.17
copilot	GitHub	1.368.0	github.copilot-1.368.0
copilot-chat	GitHub	0.31.0	github.copilot-chat-0.31.0
cpptools	ms-vscode	1.27.5	ms-vscode.cpptools-1.27.5-win32-x64
csharp	ms-dotnettools	2.90.60	ms-dotnettools.csharp-2.90.60-win32-x64
debugpy	ms-python	2025.13.2025091201	ms-python.debugpy-2025.13.2025091201-win32-x64
diff-tool	jinsihou	0.0.1	jinsihou.diff-tool-0.0.1
hexeditor	ms-vscode	1.11.1	ms-vscode.hexeditor-1.11.1
isort	ms-python	2025.0.0	ms-python.isort-2025.0.0
plantuml	jebbs	2.18.1	jebbs.plantuml-2.18.1
python	ms-python	2025.14.0	ms-python.python-2025.14.0-win32-x64
remote-explorer	ms-vscode	0.5.0	ms-vscode.remote-explorer-0.5.0
remote-ssh	ms-vscode-remote	0.120.0	ms-vscode-remote.remote-ssh-0.120.0
remote-ssh-edit	ms-vscode-remote	0.87.0	ms-vscode-remote.remote-ssh-edit-0.87.0
remote-wsl	ms-vscode-remote	0.104.1	ms-vscode-remote.remote-wsl-0.104.1
shaderlabvscodefree	amlovey	1.3.6	amlovey.shaderlabvscodefree-1.3.6
todo-tree	Gruntfuggly	0.0.226	gruntfuggly.todo-tree-0.0.226
unity-code-snippets	kleber-swf	2.4.0	kleber-swf.unity-code-snippets-2.4.0
vscode-dotnet-runtime	ms-dotnettools	2.3.7	ms-dotnettools.vscode-dotnet-runtime-2.3.7
vscode-drawio	hediet	1.9.0	hediet.vscode-drawio-1.9.0
vscode-pylance	ms-python	2025.7.1	ms-python.vscode-pylance-2025.7.1
vscode-python-envs	ms-python	1.9.12551007	ms-python.vscode-python-envs-1.9.12551007-win32-x64

C# Settings

Setting	Value
preferCSharpExtension	false
compilerDiagnosticScope	openFiles
analyzerDiagnosticScope	openFiles
enableXamlTools	true
useServerGC	true

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz (16 x 3600)
GPU Status	2d_canvas: enabled 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 trees_in_viz: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.92GB (17.59GB free)
Process Argv	--crash-reporter-id a977753a-aecd-49f4-8b92-2d95f20d59be
Screen Reader	no
VM	0%

A/B Experiments

vsliv368cf:30146710
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
996jf627:31283433
pythonrdcb7:31342333
usemplatestapi:31297334
aj953862:31281341
nesew2to5:31336538
agentclaude:31350858
nes-set-on:31351930
onetestforazureexpcf:31335614
6abeh943:31336334
envsactivate1:31353494
0927b901:31350571
ovsp_t:31383296
0cj2b977:31352657
0574c672:31362109
asdad-cf:31365767
cloudbuttont:31379625
todos-1:31384886
3efgi100_wstrepl:31382709
metis-embeddings:31385638
trigger-command-fix:31379601
auto_model_enabled:31385282

[tinylit]

I also encountered the same problem. When creating or renaming a file, a bin/obj folder is generated in the directory where the file is located, which causes the project to fail to compile successfully. I need to manually delete these two folders.

[JoeRobich]

I see that the /obj folder contains WorldManager.* files, where as, WorldManger is just a .cs file in your Scripts fodler. This appears to be the new FileBasedProgram support causing these build artifacts to be generated. cc: @RikkiGibson

You can disable this preview feature in VS Code settings while we work on a fix.

[TheMemorius]

Thanks @JoeRobich, I can confirm disabling the setting "Enable File Based Programs" is a valid workaround for now!

[RikkiGibson]

The "Dotnet Information" in the description says:

.NET SDKs installed:
No SDKs were found.

Is that accurate?

[TheMemorius]

I would say no... Perhaps this was reported because I disabled the other C#/dotnet extensions.

Now that all are enabled again, here is some output from the C# Dev Kit:

2025-09-15 18:31:17.955 [info] Starting Spawn .NET server...
2025-09-15 18:31:17.955 [info] Using dotnet resolution provided by ".NET Install Tool".
2025-09-15 18:31:17.961 [info] Starting opening a solution...
2025-09-15 18:31:17.961 [info] Starting processing the solution file "d:\Dev\Genesis\Genesis.sln" in Dev Kit server...
2025-09-15 18:31:18.403 [info] Using acquired .NET runtime at "c:\Users\svenh\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\9.0.9~x64~aspnetcore\dotnet.exe"
2025-09-15 18:31:18.445 [info] .NET Sdk found: "C:\Program Files\dotnet\dotnet.exe".
2025-09-15 18:31:20.332 [info] .NET server started and IPC established in 1783ms

And a manual check:

D:\Dev\Genesis>dotnet --version
6.0.321

D:\Dev\Genesis>dotnet sdk check
.NET SDKs:
Version      Status
----------------------------------------
2.1.818      .NET 2.1 is out of support.
3.1.426      .NET 3.1 is out of support.
6.0.321      .NET 6.0 is out of support.

Try out the newest .NET SDK features with .NET 9.0.305.

.NET Runtimes:
Name                              Version      Status
--------------------------------------------------------------------------
Microsoft.AspNetCore.All          2.1.30       .NET 2.1 is out of support.
Microsoft.AspNetCore.App          2.1.30       .NET 2.1 is out of support.
Microsoft.NETCore.App             2.1.30       .NET 2.1 is out of support.
Microsoft.AspNetCore.App          3.1.32       .NET 3.1 is out of support.
Microsoft.NETCore.App             3.1.32       .NET 3.1 is out of support.
Microsoft.WindowsDesktop.App      3.1.32       .NET 3.1 is out of support.
Microsoft.AspNetCore.App          6.0.26       .NET 6.0 is out of support.
Microsoft.NETCore.App             6.0.26       .NET 6.0 is out of support.
Microsoft.WindowsDesktop.App      6.0.26       .NET 6.0 is out of support.
Microsoft.NETCore.App             8.0.20       Up to date.
Microsoft.WindowsDesktop.App      8.0.20       Up to date.

I don't do any C# development outside of Unity though, which comes with its own toolchain. So I personally don't care if my dotnet SDKs are broken or outdated.

[RikkiGibson]

I'll try to repro in an environment with no SDKs or old SDK installed. Thanks.

If you have time, it would be useful to know if the problem recurs when the latest .NET 10 preview SDK is installed, that would help point us toward the crux of the problem.

@dibarbet it looks like we still have a "fallback path" in the language server, to support use of file-based apps, when the SDK in use is not new enough to use run-api from the SDK. That path might be misbehaving. I think we should probably drop that support at this point and give up entirely on treating any files as "file-based apps" or "rich misc files" when the SDK is too old.

[dibarbet]

@dibarbet it looks like we still have a "fallback path" in the language server, to support use of file-based apps, when the SDK in use is not new enough to use run-api from the SDK. That path might be misbehaving. I think we should probably drop that support at this point and give up entirely on treating any files as "file-based apps" or "rich misc files" when the SDK is too old.

I'm OK with that. It's nice to have, but it isn't worth putting a lot of effort in to maintain especially for a new feature.

[TheMemorius]

@RikkiGibson I installed .NET 10.0 SDK (v10.0.100-rc.1), re-enabled the dotnet.projects.enableFileBasedPrograms setting, and played around with restarting the editor and disabling/enabling the c#-related extensions for a while, as well as making changes to the code. So far the issue isn't reappearing.