Language server cannot find Unity csproj files with when using new vim.lsp.enable API

[g-371]

Hi. I'm using csharp_ls for unity development.

I initially was enabling the server with the old-style
require('lspconfig').csharp_ls.setup {}

This works correctly the LSP starts and I am able to get completions with blink.cmp

However when I changed the config to
vim.lsp.enable('csharp_ls')

The LSP fails and there is the following error when i check :LspLog

[ERROR][2025-09-23 19:09:18] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"info: Initialization[0]\r\n      initializing, csharp-ls version 0.19.0.0\r\n"
[ERROR][2025-09-23 19:09:18] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"info: Initialization[0]\r\n      csharp-ls is released under MIT license and is not affiliated with Microsoft Corp.; see https://github.com/razzmatazz/csharp-language-server\r\n"
[ERROR][2025-09-23 19:09:18] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	'info: Initialization[0]\r\n      MSBuildLocator: will register ".NET Core SDK", Version=9.0.305 as default instance\r\n'
[ERROR][2025-09-23 19:09:19] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"fail: serverEventLoop[0]\r\n      serverEventLoop: crashed with System.Exception: no or .csproj/.fsproj or sln files found on D:\\unity-project-name\\Assets\\Scripts\\Input\r\n  
[ERROR][2025-09-23 19:09:19] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"fail: serverEventLoop[0]\r\n      serverEventLoop: crashed with System.Exception: no or .csproj/.fsproj or sln files found on D:\\unity-project-name\\Assets\\Scripts\\Input\r\n  
[ERROR][2025-09-23 19:09:19] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"fail: serverEventLoop[0]\r\n      serverEventLoop: crashed with System.Exception: no or .csproj/.fsproj or sln files found on D:\\unity-project-name\\Assets\\Scripts\\Input\r\n  
[ERROR][2025-09-23 19:09:19] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"fail: serverEventLoop[0]\r\n      serverEventLoop: crashed with System.Exception: no or .csproj/.fsproj or sln files found on D:\\unity-project-name\\Assets\\Scripts\\Input\r\n  
[ERROR][2025-09-23 19:09:19] ...p/_transport.lua:36	"rpc"	"csharp-ls"	"stderr"	"fail: serverEventLoop[0]\r\n      serverEventLoop: crashed with System.Exception: no or .csproj/.fsproj or sln files found on D:\\unity-project-name\\Assets\\Scripts\\Input\r\n  

I can confirm that there are in fact .csproj and sln files in the project, and like i said when configuring it the old way everything works. So suspect this has something to do with the default configs being different.

running :LspInfo in a working session produces this:

==============================================================================
vim.lsp:                                                                    ✅

- LSP log level : WARN
- Log path: C:/Users/gwen/AppData/Local/nvim-data/lsp.log
- Log size: 3490 KB

vim.lsp: Active Clients ~
- csharp_ls (id: 1)
  - Version: 0.19.0.0
  - Root directory: D:/unity-project-name
  - Command: { "C:\\Users\\gwen\\.dotnet\\tools\\csharp-ls.EXE" }
  - Settings: vim.empty_dict()
  - Attached buffers: 1

vim.lsp: Enabled Configurations ~

vim.lsp: File Watcher ~
- File watch backend: libuv-watch

vim.lsp: Position Encodings ~
- No buffers contain mixed position encodings

where as the same :LspInfo in the non-working config produces

==============================================================================
vim.lsp:                                                                    ✅

- LSP log level : WARN
- Log path: C:/Users/gwen/AppData/Local/nvim-data/lsp.log
- Log size: 3559 KB

vim.lsp: Active Clients ~
- csharp_ls (id: 1)
  - Version: 0.19.0.0
  - Root directory: D:\unity-project-name
  - Command: { "csharp-ls" }
  - Settings: {}
  - Attached buffers: 1

vim.lsp: Enabled Configurations ~
- csharp_ls:
  - capabilities: {
      textDocument = {
        completion = {
          completionItem = {
            commitCharactersSupport = false,
            deprecatedSupport = true,
            documentationFormat = { "markdown", "plaintext" },
            insertReplaceSupport = true,
            insertTextModeSupport = {
              valueSet = { 1 }
            },
            labelDetailsSupport = true,
            preselectSupport = false,
            resolveSupport = {
              properties = { "documentation", "detail", "additionalTextEdits", "command", "data" }
            },
            snippetSupport = true,
            tagSupport = {
              valueSet = { 1 }
            }
          },
          completionList = {
            itemDefaults = { "commitCharacters", "editRange", "insertTextFormat", "insertTextMode", "data" }
          },
          contextSupport = true,
          insertTextMode = 1
        }
      }
    }
  - cmd: { "csharp-ls" }
  - filetypes: cs
  - init_options: {
      AutomaticWorkspaceInit = true
    }
  - root_dir: <function @C:/Users/gwen/AppData/Local/nvim-data/lazy/nvim-lspconfig/lsp/csharp_ls.lua:16>

vim.lsp: File Watcher ~
- File watch backend: libuv-watch

vim.lsp: Position Encodings ~
- No buffers contain mixed position encodings

Other System Info:

• OS: Windows 11
• nvim v0.11.4

For now I'm just using the deprecated API but I'd love any advice on fixing it correctly.
Thanks all!

[alsi-lawr]

Since you're still using nvim-lspconfig, you don't need to manually call vim.lsp.enable() anywhere.

Here's my Lazy config without any specific server config as an example (all you need for csharp-ls)

return {
	"neovim/nvim-lspconfig",
	event = { "BufReadPre", "BufNewFile" },
	dependencies = {
		"hrsh7th/cmp-nvim-lsp",
		{ "antosha417/nvim-lsp-file-operations", config = true },
		"mason-org/mason-lspconfig.nvim",
	},
	config = function()
		local mason_lspconfig = require("mason-lspconfig")
		local cmp_nvim_lsp = require("cmp_nvim_lsp")
		local capabilities = cmp_nvim_lsp.default_capabilities()
		local on_attach = require("alsi.core.lsp_keymaps").on_attach
		vim.diagnostic.config({
			signs = {
				text = {
					[vim.diagnostic.severity.ERROR] = "",
					[vim.diagnostic.severity.WARN] = "",
					[vim.diagnostic.severity.INFO] = "",
					[vim.diagnostic.severity.HINT] = "󰠠",
				},
			},
			jump = { float = true },
			underline = { severity = vim.diagnostic.severity.INFO },
			update_in_insert = true,
		})
		vim.lsp.config("*", {
			on_attach = on_attach,
			capabilities = capabilities,
		})
		mason_lspconfig.setup()
	end,
}

note that my alsi.core.lsp_keymaps module just declares the on_attach function with all my custom lsp-specific keymaps like <leader>ca for code actions.

[pogyomo]

I have same trouble with using vim.lsp.enable, and found a solution.

At first, the deprecated way of configuration internally sets cmd_cwd to root directory (code is here).

And curiously, this language server starts to search solution files from current directory despite root directory is passed when initialized (is it required to run this language server where solution file exists? I don't know).
@razzmatazz is it expected behavior of this language server?

So, there is two solution (these two works in my unity project)

• always launch neovim inside the directory solution file exists
• set cmd_cwd as follow

vim.lsp.config('csharp_ls', {
    cmd_cwd = vim.fs.root(0, {
        function(name, _)
            return name:match('%.sln') ~= nil
        end,
        function(name, _)
            -- fallback if no solution file found
            return name:match('%.csproj') ~= nil
        end
    })
})

I hope it help.

[razzmatazz]

@razzmatazz is it expected behavior of this language server?

Current implemention does not ingest rootPath, rootUri or workspaceFolders from initializeParams and will use process cwd as a starting point to look for sln /.csproj files (unless -s / csharp.solution arg overrides path to solution)

[razzmatazz]

There is a TODO note here:

• https://github.com/razzmatazz/csharp-language-server/blob/main/src/CSharpLanguageServer/Handlers/Initialization.fs#L62-L64

Let me push a PR that would enable support of rootPath/rootUri on initializeParams–seems to be easy to do.

[razzmatazz]

I have updated initialization sequence to actually respect rootPath & rootUri in #284

[razzmatazz]

A fix has been released as part of 0.20.0: https://www.nuget.org/packages/csharp-ls/0.20.0

[g-371]

thanks everyone! the update seems to fix the issue for me as well.