C# debugger does not apply environment variables defined in launch.json

[mtroch]

Type: Bug

Issue Description

According to the documentation at https://code.visualstudio.com/docs/csharp/debugger-settings#_environment-variables a user may set the env launch property to define environment variables but that doesn't work.

Steps to Reproduce

Define a launch configuration in your launch.json, and set some environment variables using either env or environment

{
	"name": "my-launch-configuration",
	"type": "dotnet",
	"request": "launch",  
	"projectPath": "${workspaceFolder}/src/path/to/my-project.csproj",
	"env": {
		"SOME_KEY": "some_value",
	},
	"environment": {
		"SOME_KEY": "some_value",
	},
}

Run that launch configuration from the VSCode Debugger extension. Step through the following C# statement Environment.GetEnvironmentVariable("SOME_KEY").

Expected Behavior

Environment.GetEnvironmentVariable("SOME_KEY") returns "some_value"

Actual Behavior

Environment.GetEnvironmentVariable("SOME_KEY") returns null

Also notice the launch.json opened in VSCode warns you that the env and environment properties in your configuration are not supported, it underlines them with yellow squigglies, hovering the mouse over them displays a bubble that says "Property env is not allowed". The environment property is not documented so that makes sense, but the env is documented so one would expect it to work. Those warnings are also reported in VSCode's "problems" tab.

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: 1.98.2
C# Extension: 2.69.25
Using OmniSharp: false

Dotnet Information

.NET SDK: Version: 9.0.104 Commit: 7931ad4860 Workload version: 9.0.100-manifests.dc2cb94f MSBuild version: 17.12.27+7931ad486

Runtime Environment:
OS Name: ubuntu
OS Version: 24.04
OS Platform: Linux
RID: ubuntu.24.04-arm64
Base Path: /usr/lib/dotnet/sdk/9.0.104/

.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: 7931ad4860

.NET SDKs installed:
8.0.114 [/usr/lib/dotnet/sdk]
9.0.104 [/usr/lib/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.14 [/usr/lib/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.3 [/usr/lib/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.14 [/usr/lib/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.3 [/usr/lib/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	1.17.64	ms-dotnettools.csdevkit-1.17.64-linux-arm64
csharp	ms-dotnettools	2.69.25	ms-dotnettools.csharp-2.69.25-linux-arm64
gitlens	eamodio	16.3.3	eamodio.gitlens-16.3.3
makefile-tools	ms-vscode	0.12.17	ms-vscode.makefile-tools-0.12.17
vscode-docker	ms-azuretools	1.29.4	ms-azuretools.vscode-docker-1.29.4
vscode-dotnet-runtime	ms-dotnettools	2.3.0	ms-dotnettools.vscode-dotnet-runtime-2.3.0

Extension version: 1.17.64
VS Code version: Code 1.98.2 (ddc367ed5c8936efe395cffeec279b04ffd7db78, 2025-03-12T13:32:45.399Z)
OS version: Windows_NT arm64 10.0.26100
Modes:
Remote OS version: Linux arm64 5.15.167.4-microsoft-standard-WSL2

System Info

Item	Value
CPUs	Snapdragon(R) X 12-core X1E80100 @ 3.40 GHz (12 x 2974)
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 vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: unavailable_software
Load (avg)	undefined
Memory (System)	31.57GB (13.61GB free)
Process Argv	--crash-reporter-id 6562aa1f-3698-49b6-9917-d0a2a1ddfe0f
Screen Reader	no
VM	0%

Item	Value
Remote	WSL: Ubuntu-24.04
OS	Linux arm64 5.15.167.4-microsoft-standard-WSL2
CPUs	unknown (12 x 0)
Memory (System)	15.48GB (12.30GB free)
VM	0%

[gregg-miskelly]

TLDR: You want to add your environment variables to a <project-directory>/Properties/launchSettings.json file.

Full Explanation: There are two different type values you can use to debug a C# program -- you can use dotnet, which call into the project system to determine how the specified project should be debugged, or you can use coreclr (or one of the other lower-level debug adapter types depending on what the type of project you have is) where you can fully specify how you want to debug, but you need to keep that in sync with any project changes (example: the target framework). dotnet doesn't support env (hopefully IntelliSense was giving you squiggles about this?). Instead, it pulls environment variables from the 'Properties/launchSettings.json' file, which is not just VS Code-specific, but also used by full VS, and the .NET CLI. If you need to have this specified in launch.json, you can switch to the coreclr type. In this case I would suggest using the '.NET: Generate Assets for Build and Debug' command from the command well, as that will give you a good launch.json template to start from.