`dotnet.generateAssets` persists C# Dev Kit temporary solution paths in build and publish tasks

[bwateratmsft]

Type: Bug

Summary

dotnet.generateAssets can persist C# Dev Kit’s temporary solution path in generated tasks instead of the application’s .csproj. This produces machine-specific configuration and, when the workspace and temporary solution are on different Windows drives, an invalid path.

This affects Container Tools’ Add Docker Files to Workspace command, which delegates .NET asset generation to the C# extension. Tracked downstream in microsoft/vscode-containers#605.

Steps to reproduce

1. Install the C# and C# Dev Kit extensions.
2. Create an ASP.NET Core project without a solution file on a drive different from VS Code’s user-data directory:

   dotnet new mvc -o D:\Sandbox\ExampleApp

3. Open that folder in VS Code and allow Dev Kit to load it in workspace mode.
4. Run Containers: Add Docker Files to Workspace, selecting ASP.NET Core and Linux.
5. Inspect the generated .vscode/tasks.json and run the build task.

Container Tools invokes:

vscode.commands.executeCommand(
    'dotnet.generateAssets',
    undefined,
    { skipPrompt: true }
);

Reproduced with:

• Container Tools 2.5.0
• C# 2.140.9
• C# Dev Kit 3.20.207
• .NET SDK 10.0.400
• Windows, with the project on D: and VS Code user data on C:

Actual behavior

The generated build, publish, and watch tasks reference a path shaped like:

./${workspaceFolder}/c:/Users/<user>/AppData/Roaming/Code/User/workspaceStorage/<id>/ms-dotnettools.csdevkit/ExampleApp.sln

The build fails with:

MSBUILD : error MSB1009: Project file does not exist.

The original temporary solution does exist on C:. The generated argument is malformed. Building the actual .csproj succeeds.

Even without the cross-drive failure, persisting a solution under VS Code’s workspace storage makes the configuration dependent on the generating user’s environment.

Expected behavior

Persist the selected project’s workspace-relative path in build, publish, and watch tasks, regardless of whether Dev Kit is installed:

${workspaceFolder}/ExampleApp.csproj

Checked-in configuration should work for teammates using the C# extension and .NET SDK without requiring Dev Kit or its generated temporary solution.

Investigation

In src/shared/assets.ts:

• getBuildProjectPath() prefers any nonempty solutionPath over projectPath.
• getBuildPath() unconditionally joins ${workspaceFolder} with path.relative(workspace, target). Across Windows drives, the latter returns an absolute path, making the join invalid.

Solution preference was introduced by commit 7fb0321. Dev Kit’s solution-free workspace behavior exposes this by creating solutions outside the workspace.

#9704 already changes watch to use the project path. Build and publish still prefer the solution.

Suggested resolution

Prefer project paths for newly generated persisted tasks, leaving existing user-authored tasks unchanged.

If solution-based build/publish defaults must be retained, please expose a supported dotnet.generateAssets option to request project-based tasks. Currently, selectedIndex selects a project but does not override solution preference, and skipPrompt only controls the Dev Kit recommendation dialog.

Such an option would let Container Tools request portable configuration without duplicating C# asset generation or post-processing tasks.json and launch.json.

Extension version: 2.140.9
VS Code version: Code 1.137.0 (645f29cc3176500b4b5762ba887cf2a7f0ffdf2c, 2026-09-08T13:43:59-07:00)
OS version: Windows_NT x64 10.0.26200
Modes:

Logs

C# log

Details

2026-09-10 12:01:59.170 [info] Locating .NET runtime version 10.0.5
2026-09-10 12:01:59.455 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2026-09-10 12:01:59.455 [info] Activating C# + C# Dev Kit...
2026-09-10 12:02:00.047 [info] info: Program[0]
2026-09-10 12:02:00.047 [info]       Server started with process ID 9236
2026-09-10 12:02:00.875 [info] [Program] Language server initialized
2026-09-10 12:02:00.877 [info] [Program] Monitoring client process 9804 for exit
2026-09-10 12:02:01.531 [info] [initialized] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsEntryPointDiscovery] Finished discovery in 'd:\Sandbox\ContainersIssue605-55ffe9f3' in 9 milliseconds
2026-09-10 12:02:04.881 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\Sandbox\ContainersIssue605-55ffe9f3\ContainersIssue605.csproj loaded by C# Dev Kit

C# LSP Trace Logs log

Details

Environment Information

VSCode version: 1.137.0
C# Extension: 2.140.9
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 10.0.400 Commit: 14fbf8d527 Workload version: 10.0.400-manifests.b0ae88bd MSBuild version: 18.9.6+14fbf8d52

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26200
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.400\

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.12
Architecture: x64
Commit: 95017c711e

.NET SDKs installed:
8.0.425 [C:\Program Files\dotnet\sdk]
9.0.318 [C:\Program Files\dotnet\sdk]
10.0.400 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.12 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
DOTNET_CLI_UI_LANGUAGE [en-US]

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
azure-dev	ms-azuretools	0.10.0	ms-azuretools.azure-dev-0.10.0
csdevkit	ms-dotnettools	3.20.207	ms-dotnettools.csdevkit-3.20.207-win32-x64
csharp	ms-dotnettools	2.140.9	ms-dotnettools.csharp-2.140.9-win32-x64
debugpy	ms-python	2026.6.0	ms-python.debugpy-2026.6.0-win32-x64
esbuild-problem-matchers	connor4312	0.0.3	connor4312.esbuild-problem-matchers-0.0.3
memento-explorer	bwater	0.1.7	bwater.memento-explorer-0.1.7
native-preview	TypeScriptTeam	0.20260708.2	typescriptteam.native-preview-0.20260708.2-win32-x64
python	ms-python	2026.4.0	ms-python.python-2026.4.0-win32-x64
remote-containers	ms-vscode-remote	0.469.0	ms-vscode-remote.remote-containers-0.469.0
remote-explorer	ms-vscode	0.5.0	ms-vscode.remote-explorer-0.5.0
remote-ssh	ms-vscode-remote	0.128.0	ms-vscode-remote.remote-ssh-0.128.0
remote-ssh-edit	ms-vscode-remote	0.87.0	ms-vscode-remote.remote-ssh-edit-0.87.0
vscode-azure-github-copilot	ms-azuretools	1.0.231	ms-azuretools.vscode-azure-github-copilot-1.0.231-win32-x64
vscode-azure-mcp-server	ms-azuretools	2.0.46	ms-azuretools.vscode-azure-mcp-server-2.0.46-win32-x64
vscode-azureappservice	ms-azuretools	0.27.0	ms-azuretools.vscode-azureappservice-0.27.0
vscode-azurefunctions	ms-azuretools	1.22.1	ms-azuretools.vscode-azurefunctions-1.22.1
vscode-azureresourcegroups	ms-azuretools	0.12.7	ms-azuretools.vscode-azureresourcegroups-0.12.7
vscode-containers	ms-azuretools	2.5.0	ms-azuretools.vscode-containers-2.5.0
vscode-dotnet-runtime	ms-dotnettools	3.1.0	ms-dotnettools.vscode-dotnet-runtime-3.1.0
vscode-eslint	dbaeumer	3.0.34	dbaeumer.vscode-eslint-3.0.34
vscode-pull-request-github	GitHub	0.166.0	github.vscode-pull-request-github-0.166.0
vscode-pylance	ms-python	2026.3.1	ms-python.vscode-pylance-2026.3.1
vscode-remote-extensionpack	ms-vscode-remote	0.26.0	ms-vscode-remote.vscode-remote-extensionpack-0.26.0
vscode-yaml	redhat	1.24.0	redhat.vscode-yaml-1.24.0

C# Settings

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

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz (20 x 3696)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x8086, DEVICE=0x9bc5 [Intel(R) UHD Graphics 630], DRIVER_VENDOR=Intel, DRIVER_VERSION=30.0.101.1273 ACTIVE GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.9278 Machine model name: Machine model version: 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 webgl: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	126.84GB (102.06GB free)
Process Argv	--log ms-azuretools.azureextensionui=trace --log ms-azuretools.vscode-containers=debug --log ms-azuretools.vscode-azure=debug --crash-reporter-id 346e43a8-9268-4087-a447-da84e0fdc384
Screen Reader	yes
VM	0%

[bwateratmsft]

Example tasks.json with mangled paths:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build",
            "command": "dotnet",
            "type": "process",
            "args": [
                "build",
                "./${workspaceFolder}/c:/Users/username/AppData/Roaming/Code/User/workspaceStorage/22c32d0c33cd5e83b81d8a0fec294120/ms-dotnettools.csdevkit/ContainersIssue605-55ffe9f3.sln",
                "/property:GenerateFullPaths=true",
                "/consoleloggerparameters:NoSummary;ForceNoAlign"
            ],
            "problemMatcher": "$msCompile"
        },
        // ...
    ]
}

How it used to look (though with different project name):

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build",
            "command": "dotnet",
            "type": "process",
            "args": [
                "build",
                "${workspaceFolder}/Net10MVC.csproj",
                "/property:GenerateFullPaths=true",
                "/consoleloggerparameters:NoSummary;ForceNoAlign"
            ],
            "problemMatcher": "$msCompile"
        },
        // ...
    ]
}