How can I use the vsdbg adapter?

[arkaragian]

I am trying to implement a plugin for C# support in neovim. One feature that I would really like to implement would be to be able to
execute a single unit test that contains a breakpoint. I cannot figure how to make this with the netcoredbg project and I was experimenting with https://github.com/OmniSharp/omnisharp-vscode. If you download the release and unzip the file you get access
to the vsdbg executable that seems to have the same interface with the netcoredbg executable. So I made an adapter:

dap.adapters.vsdbg= {
  type = 'executable',
  command = 'vsdbg',
  args = {'--interpreter=vscode', '--engineLogging='..home..'/vsdbg.log'},
}

and in my cs configuration:

dap.configurations.cs = {
    {
        --type = "netcoredbg",
        type = "vsdbg",
        name = "Launch CS Debugger",
        request = "launch",
        program = vim.fn.input('Path to dll: ', vim.fn.getcwd() .. '/bin/', 'file')
        end
    }
}

and tried to execute a test.dll and got the following error:

E5108: Error executing lua ...kar\AppData\Local\nvim-data\plugged\nvim-dap/lua/dap.lua:484: ...ata\Local\nvim-data\plugged\nvim-dap/lua/dap/session.lua:1217: Error running vsdbg: ENOENT: no such file or directory

Bellow are the logs I feel that there must be a mismatch on the sequences or the vscode debuger refuses to speak to non vscode dap clients. Has anyone tried this before?
Command Seq 0:

{
  "type": "request",
  "command": "initialize",
  "seq": 0,
  "arguments": {
    "clientId": "neovim",
    "clientname": "neovim",
    "adapterID": "nvim-dap",
    "pathFormat": "path",
    "columnsStartAt1": true,
    "linesStartAt1": true,
    "supportsRunInTerminalRequest": true,
    "supportsVariableType": true,
    "supportsProgressReporting": true,
    "locale": "en_US"
  }
}

Response Seq 1:

{
  "seq": 1,
  "type": "response",
  "request_seq": 0,
  "success": false,
  "command": "initialize",
  "message": "",
  "body": {
    "supportsConfigurationDoneRequest": true,
    "supportsFunctionBreakpoints": true,
    "supportsConditionalBreakpoints": true,
    "supportsHitConditionalBreakpoints": true,
    "supportsEvaluateForHovers": true,
    "exceptionBreakpointFilters": [
      {
        "filter": "all",
        "label": "All Exceptions",
        "description": "Break when an exception is thrown. ",
        "default": false,
        "supportsCondition": true
      }
    ],
    "supportsSetVariable": true,
    "supportsGotoTargetsRequest": true,
    "supportsModulesRequest": true,
    "additionalModuleColumns": [
      {
        "attributeName": "vsLoadAddress",
        "label": "Load Address",
        "type": "string"
      },
      {
        "attributeName": "vsPreferredLoadAddress",
        "label": "Preferred Load Address",
        "type": "string"
      },
      {
        "attributeName": "vsModuleSize",
        "label": "Module Size",
        "type": "number"
      },
      {
        "attributeName": "vsLoadOrder",
        "label": "Order",
        "type": "number"
      },
      {
        "attributeName": "vsTimestampUTC",
        "label": "Timestamp",
        "type": "unixTimestampUTC"
      },
      {
        "attributeName": "vsIs64Bit",
        "label": "64-bit",
        "type": "boolean"
      }
    ],
    "supportedChecksumAlgorithms": [
      "MD5",
      "SHA1",
      "SHA256"
    ],
    "supportsExceptionOptions": true,
    "supportsValueFormattingOptions": true,
    "supportsExceptionInfoRequest": true,
    "supportTerminateDebuggee": true,
    "supportsSetExpression": true,
    "supportsReadMemoryRequest": true,
    "supportsCancelRequest": true,
    "supportsExceptionFilterOptions": true,
    "supportsExceptionConditions": true,
    "supportsLoadSymbolsRequest": true,
    "supportsModuleSymbolSearchLog": true,
    "supportsDebuggerProperties": true,
    "supportsSetSymbolOptions": true,
    "supportsHitBreakpointIds": true,
    "supportsVsIndividualBreakpointOperations": true,
    "supportsVsBreakpointLanguage": true,
    "supportsSetHitCount": true,
    "supportsVsCustomMessages": true,
    "supportsEvaluationOptions": true,
    "supportsExceptionStackTrace": true,
    "memoryReferencesAreAddresses": true,
    "supportsObjectFavorites": true,
    "supportsObjectId": true,
    "supportsVariableEnumerators": false
  }
}

Command Seq 1:

{
  "type": "request",
  "command": "disconnect",
  "seq": 1,
  "arguments": {
    "terminateDebuggee": true,
    "restart": false
  }
}

Event Seq 2:

{
  "seq": 2,
  "type": "event",
  "event": "output",
  "body": {
    "category": "telemetry",
    "output": "VS/Diagnostics/Debugger/vsdbg/DebugCompleted",
    "data": {
      "VS.Diagnostics.Debugger.vsdbg.OSFamily": "Windows",
      "VS.Diagnostics.Debugger.vsdbg.Version": "unknown",
      "VS.Diagnostics.Debugger.vsdbg.WindowsVersion": "10.0.19044",
      "VS.Diagnostics.Debugger.vsdbg.DebugCompleted.BreakCounter": 0,
      "VS.Diagnostics.Debugger.vsdbg.AdapterId": "unknown"
    }
  }
}

Response Seq 3

{
  "seq": 3,
  "type": "response",
  "request_seq": 1,
  "success": true,
  "command": "disconnect"
}

[mfussenegger]

Error running vsdbg: ENOENT: no such file or directory

vsdbg is not in your $PATH. You need to add it or specify the absolute path to it.

[arkaragian]

Hello! Thank you for your reply. I have verified that vsdbg is in by path now I just get a vim notification with the message

ERROR Could not initialize debug adapter

The Dap log displays:

[ INFO ] 2023-02-23T23:17:29Z+0200 ] ...ata\Local\nvim-data\plugged\nvim-dap/lua/dap/session.lua:695 ]	"Telemetry"	"VS/Diagnostics/Debugger/vsdbg/DebugCompleted"
[ INFO ] 2023-02-23T23:17:29Z+0200 ] ...ata\Local\nvim-data\plugged\nvim-dap/lua/dap/session.lua:1584 ]	"Session closed due to disconnect"

at this point I don't know if vsdbg refuses to speak to non vscode adapters or if there is a real issue here.

[mfussenegger]

Is there nothing else in the logs? Can you try changing the log level to trace?

[lawrence-laz]

Have you managed to get this running?

[arkaragian]

Hello. To be honest I have yet to find time to really have a look into the issue. This question relates to my effort to really adopt neovim for everyday development as a replacement for VSCode or VS on a windows machine. @mfussenegger has been very helpful. But I really need to research this more.

[pinbraerts]

Launched vsdbg.exe with

dap.adapters.cppvsdbg = {
    id = 'cppvsdbg',
    type = 'executable',
    command = 'D:\\vscode\\cppdbg\\extension\\debugAdapters\\vsdbg\\bin\\vsdbg.exe',
    args = {
        '--interpreter=vscode',
    },
    options = { detached = false, },
}
dap.set_log_level 'trace' -- for log output

Also tried to mimic vscode in nvim-dap/lua/dap/session.lua (1647)

    clientId = 'vscode';
    clientname = 'Visual Studio Code';

In all cases vsdbg.exe rejects the handshake with a quote from the license:

You may only use the C/C++ Extension for Visual Studio Code
with Visual Studio Code, Visual Studio or Visual Studio for Mac
software to help you develop and test your applications.

dap.log

[ DEBUG ] 2023-07-15T22:32:38Z+0300 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:1605 ]	"request"	{
  arguments = {
    clientId = "vscode",
    clientname = "vscode",
    cwd = "C:\\Users\\pinbraerts\\src",
    name = "Launch file",
    program = "main.exe",
    request = "launch",
    stopAtEntry = false,
    type = "cppvsdbg"
  },
  command = "launch",
  seq = 1,
  type = "request"
}
[ DEBUG ] 2023-07-15T22:32:38Z+0300 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:936 ]	4	{
  arguments = {
    value = "l5mmDzf3TIVR9Mrc4TdFk6Y/jea4WMQHZ9gRvxesbN8="
  },
  command = "handshake",
  seq = 2,
  type = "request"
}
[ WARN ] 2023-07-15T22:32:38Z+0300 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:994 ]	"No handler for reverse request"	{
  arguments = {
    value = "l5mmDzf3TIVR9Mrc4TdFk6Y/jea4WMQHZ9gRvxesbN8="
  },
  command = "handshake",
  seq = 2,
  type = "request"
}
[ DEBUG ] 2023-07-15T22:32:38Z+0300 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:936 ]	4	{
  body = {
    category = "console",
    output = "-------------------------------------------------------------------\nYou may only use the C/C++ Extension for Visual Studio Code\nwith Visual Studio Code, Visual Studio or Visual Studio for Mac\nsoftware to help you develop and test your applications.\n-------------------------------------------------------------------\n",
    severity = "ok"
  },
  event = "output",
  seq = 3,
  type = "event"
}

[tsioryhaja]

The debug adapter actually use that handshake to verify if you are using it with VSCode or not. so you will need to respond to that handshake request if you want it to work.

I don't know for .Net as I'm not really into it but for C/C++, this is how I do it:
First thing, you will need to have VSCode installed with the cpptools extension.
Next, you need to make a node js code to sign the handshake request value. It uses a custom Native Nodejs plugin so we wont easily make a copy of it in another language. This is a exemple of what I use written in typescript:

declare module vsda {
	export class signer {
		sign(arg: string): string;
	}
	export class validator {
		createNewMessage(arg: string): string;
		validate(arg: string): 'ok' | 'error';
	}
}
const vsda_location = '[VSCODE_INSTALL_DIR]\\resources\\app\\node_modules.asar.unpacked\\vsda\\build\\Release\\vsda.node';
const a: typeof vsda = require(vsda_location);
const signer: vsda.signer = new a.signer();
process.argv.forEach((value, index, array) => {
  if (index >= 2) {
    const r = signer.sign(value);
    console.log(r);
  }
});

And next, you will need to make a handler for the handshake request that use the node js code we just made.
I use something like this with "sign.js" being the transpiled version of the typescript code above:

local utils = require('dap.utils')

local rpc = require('dap.rpc')

local function send_payload(client, payload)
  local msg = rpc.msg_with_content_length(vim.json.encode(payload))
  client.write(msg)
end

function RunHandshake(self, request_payload)
  local signResult = io.popen('node C:\\debugadapter\\vsdbgsignature\\sign.js ' .. request_payload.arguments.value)
  if signResult == nil then
    utils.notify('error while signing handshake', vim.log.levels.ERROR)
    return
  end
  local signature = signResult:read("*a")
  signature = string.gsub(signature, '\n', '')
  local response = {
    type = "response",
    seq = 0,
    command = "handshake",
    request_seq = request_payload.seq,
    success = true,
    body = {
      signature = signature
    }
  }
  send_payload(self.client, response)
end

Next for my debug adapter setup I use this:

dap.adapters.cppvsdbg = {
	id='cppvsdbg',
	type='executable',
  command = '[USER_PROFILE_LOCATION]\\.vscode\\extensions\\ms-vscode.cpptools-1.18.5-win32-x64\\debugAdapters\\vsdbg\\bin\\vsdbg.exe',
  args = { "--interpreter=vscode" },
	options = {
    externalTerminal = true,
    -- logging = {
    --   moduleLoad = false,
    --   trace = true
    -- }
	},
  runInTerminal =  true,
  reverse_request_handlers = {
    handshake = RunHandshake,

  },
}

and for the configuration I use this:

dap.configurations.cpp = {
  {
    name = 'Try vsdbg',
    type = "cppvsdbg",
    request = "launch",
    program = function ()
      return vim.fn.input('Path: ', vim.fn.getcwd() .. '\\Debug\\test.exe', 'file')
    end,
    cwd = vim.fn.getcwd(),
    clientID = 'vscode',
    clientName = 'Visual Studio Code',
    externalTerminal = true,
    columnsStartAt1 = true,
    linesStartAt1 = true,
    locale = "en",
    pathFormat = "path",
    externalConsole = true
    -- console = "externalTerminal"
  },
}

and last thing, it's to be discussed but I noticed that the "stackTrace" request actually result in an error. This is I think to be discussed with the owner of the lib what he think should be done but it actually have some difference with the specification of the DAP.

I the specification, in the "stackTrace" arguments, the field "startFrame" is not required and should be used as a 0 by the debug adapter if not specified. But vsdbg actually require you to specify it. So for the moment, I modified a bit my local copy of nvim-dap to set this field to 0. But I don't know if the lib actually want that too.

[lawrence-laz]

Has anyone gotten this to work with .NET?

[adambasis]

@tsioryhaja Thank you so much for this walkthrough! With this guide, I could get it to work fairly quickly.

I the specification, in the "stackTrace" arguments, the field "startFrame" is not required and should be used as a 0 by the debug adapter if not specified. But vsdbg actually require you to specify it. So for the moment, I modified a bit my local copy of nvim-dap to set this field to 0. But I don't know if the lib actually want that too.

@mfussenegger Do you think this is something that should be in main?

Specifically it's in lua/dap/session.lua line 706:
local err, response = self:request('stackTrace', { startFrame = 0, threadId = stopped.threadId; })

(Notice that startFrame = 0 was added to the original code)

Without this, the vsdbg.exe debugger does not work. If it does not affect anything else, I assume it should be fine adding this? I do understand if not though, because this really is an edge case.

Possibly as a configuration option?

By the way, thank you for all your awesome plugins!

[tsioryhaja]

Happy I could help.

@lawrence-laz I just tried with a minimal code for C#. I don't know if it will work on a bigger project but to get it work for a .Net core project (still not able to do it for .Net framework project) I did this:

First instead of installing the cpptools plugin you should install the c# plugin and use the vsdbg-ui.exe executable inside it.
It should be something like this depending of the version of the installed plugins:
C:\Users\user_name.vscode\extensions\ms-dotnettools.csharp-2.39.29-win32-x64.debugger\x86_64\vsdbg-ui.exe.

Everything else is the same, you will have to build your project first then for the program field in the configuration, you should use the exe file that was generated.
for my test I used something like this:
program=function () return vim.fn.input('Path: ', vim.fn.getcwd() .. '\\bin\\Debug\\net7.0\\test.exe', 'file') end,
I will test for a ASP.Net core project when I have the time but for a small minimal console program it works.

[marcinjahn]

@tsioryhaja I followed your steps (for .NET C#), and it fails on initialization of debugging session.
I have this log:

[DEBUG] 2025-05-04 09:11:40 dap/session.lua:1514	"Spawning debug adapter"	{
  args = { "--interpreter=vscode" },
  command = "/home/mnj/bin/vsdbg-old/vsdbg-ui",
  id = "csvsdbg",
  options = {
    externalTerminal = true,
    logging = {
      moduleLoad = true,
      trace = true
    }
  },
  reverse_request_handlers = {
    handshake = <function 1>
  },
  runInTerminal = true,
  type = "executable"
}
[DEBUG] 2025-05-04 09:11:40 dap/session.lua:1853	"request"	{
  arguments = {
    adapterID = "csvsdbg",
    clientID = "neovim",
    clientName = "neovim",
    columnsStartAt1 = true,
    linesStartAt1 = true,
    locale = "en_US.UTF-8",
    pathFormat = "path",
    supportsProgressReporting = true,
    supportsRunInTerminalRequest = true,
    supportsStartDebuggingRequest = true,
    supportsVariableType = true
  },
  command = "initialize",
  seq = 1,
  type = "request"
}
[DEBUG] 2025-05-04 09:11:40 dap/session.lua:1049	1	{
  body = {
    category = "telemetry",
    data = {
      ["VS.Diagnostics.Debugger.vsdbg.AdapterId"] = "unknown",
      ["VS.Diagnostics.Debugger.vsdbg.Command"] = "initialize",
      ["VS.Diagnostics.Debugger.vsdbg.Distribution.Name"] = "fedora",
      ["VS.Diagnostics.Debugger.vsdbg.Distribution.Version"] = "42",
      ["VS.Diagnostics.Debugger.vsdbg.ErrorCode"] = -2147467259,
      ["VS.Diagnostics.Debugger.vsdbg.OSFamily"] = "Linux",
      ["VS.Diagnostics.Debugger.vsdbg.Version"] = "unknown"
    },
    output = "VS/Diagnostics/Debugger/vsdbg/CommandFailed"
  },
  event = "output",
  seq = 1,
  type = "event"
}

The thing that is a bit odd is:

    clientID = "neovim",
    clientName = "neovim",

In the adapter configuration I copied from your example, you specifically set:

    clientID = 'vscode',
    clientName = 'Visual Studio Code',

but somehow it's not used? Did anything change in dap in the meantime? I tried to "force" the correct values by modifying dap source code, but even with those values set, the initializaton fails all the same.

On the vsdbg side, I tried to use exactly the same version you used in your example (2.39.29), but that did not help.

[lilian-lilifox]

same do i

[cagechi]

Excellent!!
It worked both .Net and dotnet-script.
But I see that the standard output is not output to dap console, but to the background terminal.

[cagechi]

require('dap').defaults.fallback.exception_breakpoints = { "raised" } does not work.
If I call require(“dap”).set_exception_breakpoints() after the session starts, it works.
I tried the following, but it still does not work.

dap.listeners.after.event_initialized["set_exception_breakpoints"] = function() 
  dap.set_exception_breakpoints({"raised", "uncaught"}) 
end

Is there any way to handle this?

[Inurias]

@cagechi could you please share your C# DAP config? I adapted the above C++ example for C# using the vscode-csharp plugin, but the initialize request fails when starting the debug session, like it does for @marcinjahn

[cagechi]

@Inurias

My DAP config is as follows.

-- vsdbg certification
local function send_payload(client, payload)
  local msg = rpc.msg_with_content_length(vim.json.encode(payload))
  client.write(msg)
end

-- See https://github.com/mfussenegger/nvim-dap/discussions/869#discussioncomment-8121995 for contents of file vsdbgsignature
local SIGNJS = CONFIG_PATH:gsub("/", "\\") .. "\\vsdbgsignature.js"

function RunHandshake(self, request_payload)
  local signResult = io.popen("node " .. SIGNJS .. " " .. request_payload.arguments.value)
  if signResult == nil then
    dap_utils.notify('error while signing handshake', vim.log.levels.ERROR)
    return
  end
  local signature = signResult:read("*a")
  signature = string.gsub(signature, '\n', '')
  local response = {
    type = "response",
    seq = 0,
    command = "handshake",
    request_seq = request_payload.seq,
    success = true,
    body = {
      signature = signature
    }
  }
  send_payload(self.client, response)
end

dap.adapters.coreclr = {
  id = 'coreclr',
  type = 'executable',
  command = "vsdbg-ui.exe path", -- Note: Please include the actual path!
  args = {
    "--interpreter=vscode",
    -- "--engineLogging",
    -- "--consoleLogging",
  },
  options = {
    externalTerminal = true,
  },
  runInTerminal = true,
  reverse_request_handlers = {
    handshake = RunHandshake,
  },
}

dap.configurations.cs = {
    type = "coreclr",
    name = "Launch",
    request = "launch",
    program = "dotnet exe path",-- Note: Please include the actual path!
    args = {},
    cwd = vim.fn.getcwd(),
    clientID = 'vscode',
    clientName = 'Visual Studio Code',
    externalTerminal = true,
    columnsStartAt1 = true,
    linesStartAt1 = true,
    locale = "en",
    pathFormat = "path",
    externalConsole = true
}

[NeuSandeZ]

@marcinjahn Did you get it working by any chance for .net?

[kmiterror]

I made a neovim plugin that works with ".net core compatible" debuggers
It should work with: ASP.NET Core, .NET Core and .NET for Android (iOS should also be doable)
Have a look:
https://github.com/kmiterror/dotnet-debug.nvim

[NeuSandeZ]

Dude, you are golden! It works perfectly for me.

[NeuSandeZ]

@kmiterror
Hey, I've seen in your plugin that you commented out the monovsdbg configuration for android debugging. Is there any chance you could help me with setting that up for iPhone simulator?

dotnet build -t:Build -p:Configuration=Debug -r iossimulator-arm64 -p:CustomAfterMicrosoftCSharpTargets="/Users/wojciechmassalski/.vscode/extensions/ms-dotnettools.dotnet-maui-1.11.215-darwin-arm64/dist/resources/Custom.After.Microsoft.CSharp.targets" -p:MauiVSCodeBuildOutputFile="/var/folders/ht/xy6q8gm54vzbvsh8bnnyjlqm0000gn/T/dotnet-maui/maui-vsc-70117e65-1d4c-4383-ad8f-cc137b791a68.json" -p:MauiTargetProject="/Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/iOSApp1.csproj" /Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/iOSApp1.csproj 

/Users/wojciechmassalski/.local/share/mise/installs/dotnet/10.0.100/packs/Microsoft.iOS.Sdk.net10.0_26.1/26.1.10494/tools/bin/../lib/mlaunch/mlaunch.app/Contents/MacOS/mlaunch -sdkroot /Applications/Xcode.app/Contents/Developer \
--launchsim /Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/bin/Debug/net10.0-ios/iossimulator-arm64/iOSApp1.app \
--argument=-monodevelop-port \
--argument=65217 \
--setenv=__XAMARIN_DEBUG_MODE__=wifi \
--setenv=__XAMARIN_DEBUG_PORT__=65217 \
--device=:v2:udid=D429B0C2-2971-4AD2-A9E9-1661107BCBF1 \
--wait-for-exit:true

/Users/wojciechmassalski/Library/Application Support/Code/User/globalStorage/ms-dotnettools.vscode-dotnet-runtime/.dotnet/9.0.11~arm64/dotnet ./dist/DebugServer/DebugServer.dll \
name:C#: \
iOSApp1 \
type:monovsdbg \
request:launch \
brokeredServicePipeName:/tmp/13520351-9786-4a6e-9e38-776d240d1a0b \
noDebug:false \
sessionId:77cfb21c-8f17-48d6-ace8-45b36228be66 \
preLaunchTask:maui: \
Build workspaceDirectory:/Users/wojciechmassalski/Projects/iOSApp1 \
project:/Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/iOSApp1.csproj \
platform:ios \
debugTarget:D429B0C2-2971-4AD2-A9E9-1661107BCBF1 \
isEmulator:true \
platformArchitecture:arm64 \
configuration:Debug \
isMaui:false \
isMultiplatform:true \
dotnetVersion:10.0.100 \
isMultiPlatform:false \
targetFramework:net10.0-ios \
dotnetPath:/Users/wojciechmassalski/.local/share/mise/installs/dotnet/10.0.100 \
device:D429B0C2-2971-4AD2-A9E9-1661107BCBF1 \
runtimeIdentifier:iossimulator-arm64 \
skipDebug:false \
debugPort:65217 \
useVSDbg:true \
_mauiBuildOutputPropsFile:/var/folders/ht/xy6q8gm54vzbvsh8bnnyjlqm0000gn/T/dotnet-maui/maui-vsc-70117e65-1d4c-4383-ad8f-cc137b791a68.json \
monoDebuggerOptions:ip:127.0.0.1 \
monoDebuggerOptions:port:65217 \
monoDebuggerOptions:platform:ios \
monoDebuggerOptions:isServer:true \
monoDebuggerOptions:assetsPath:/Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/bin/Debug/net10.0-ios/iossimulator-arm64/iOSApp1.app/ \
program:/Users/wojciechmassalski/Projects/iOSApp1/iOSApp1/bin/Debug/net10.0-ios/iossimulator-arm64/iOSApp1.dll \
justMyCode:true \
symbolOptions: \
requireExactSource:true \
sourceFileMap:{} \
enableStepFiltering:true

Could you help me a bit with it? My endeavours seems not to come to fruition :(