matlab_ls connection times out from neovim and possibly vscode

[nickcounts]

neovim lsp detects Matlab project, starts ls, fails to establish connection. :LspInfo shows matlab_ls as active client, version (no serverInfo.version response).

As far as I can tell, nvim is able to launch matlab-language-server, there is socket connectivity as demonstrated by curl from :terminal inside neovim. Running matlab-language-server --stdio from :terminal produces a reasonable looking response.

Attempted to use --sockets with the socket found from lsof. When I do that, the :LspLog line shows a MASSIVE line that appears to be some kind of minified javascript. The source is matlab-language-server/out/index.js and the line terminates mid-statement. It looks incomplete, so I opened the index.js file to see if it was malformed and found TONS of crazy looking things in the file, tons of Chinese characters, a bajillion (scientific term) random looking URLs, and so much more. It looks like roughly 2 megs of text.

• lspLog-socket.log
• index.js

It's possible that my log is simply breaking, and that the entire well-formed js string is being passed, but I can't tell. It's obviously too big to paste here. I poked through the language server repository and my local copy and I can't figure out where that could possibly be coming from. There must be some dependency that is generating it. Hopefully that's not important, but I thought it was odd enough to mention.

I'm really at a loss. I can launch matlab-language-server from vim terminal, I can curl it and get a good response. The connection just appears to be timing out. I am using the old desktop. Really can't think of what else to do, but I'm /dying/ without the language server. I can't handle the Matlab editor without my vim bindings - I keep typing :w and long strings of jjjjjjjjj all over the place.

:LspInfo shows

vim.lsp: Active Clients ~
- matlab_ls (id: 1)
  - Version: ? (no serverInfo.version response)
  - Root directory:
      ~/Documents/MATLAB/MDRT
  - Command: { "matlab-language-server", "--stdio" }
  - Settings: {
      MATLAB = {
        indexWorkspace = false,
        installPath = "/Applications/MATLAB_R2024a.app",
        matlabConnectionTiming = "onStart",
        prewarmGraphics = false,
        telemetry = false
      }
    }
  - Attached buffers: 21

:LspLog shows

[START][2026-01-19 21:04:08] LSP logging initiated
[ERROR][2026-01-19 21:04:08] .../nvim-macos-arm64/share/nvim/runtime/lua/vim/lsp/log.lua:151	"rpc"	"matlab-language-server"	"stderr"	"(node:38664) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.\n(Use `node --trace-deprecation ...` to show where the warning was created)\n"
[WARN][2026-01-19 21:04:08] .../nvim-macos-arm64/share/nvim/runtime/lua/vim/lsp/log.lua:151	"The language server matlab_ls triggers a registerCapability handler for workspace/didChangeConfiguration despite dynamicRegistration set to false. Report upstream, this warning is harmless"
[WARN][2026-01-19 21:04:08] .../nvim-macos-arm64/share/nvim/runtime/lua/vim/lsp/log.lua:151	"The language server matlab_ls triggers a registerCapability handler for workspace/didChangeWorkspaceFolders despite dynamicRegistration set to false. Report upstream, this warning is harmless"
[ERROR][2026-01-19 21:04:12] .../nvim-macos-arm64/share/nvim/runtime/lua/vim/lsp/log.lua:151	"rpc"	"matlab-language-server"	"stderr"	"(node:38664) [DEP0169] DeprecationWarning: `url.parse()` behavior is not standardized and prone to errors that have security implications. Use the WHATWG URL API instead. CVEs are not issued for `url.parse()` vulnerabilities.\n"
[ERROR][2026-01-19 21:04:15] .../nvim-macos-arm64/share/nvim/runtime/lua/vim/lsp/log.lua:151	"(21:04:15) matlabls - ERROR: Timeout when attaching to release: 24a"

> lsof -i -P -n | grep -i matlab
MATLAB    38667 nick  639u  IPv4 0xbcfa5d52e3368be1      0t0    TCP 127.0.0.1:31515 (LISTEN)
MATLAB    38667 nick  647u  IPv4 0x8675f70308af4699      0t0    TCP 10.0.1.129:62427->23.3.132.61:443 (ESTABLISHED)
MATLAB    38667 nick  649u  IPv4 0xb705cb57e1d56745      0t0    TCP 127.0.0.1:31515->127.0.0.1:62428 (ESTABLISHED)

> curl -k -v https://127.0.0.1:31515
*   Trying 127.0.0.1:31515...
* Connected to 127.0.0.1 (127.0.0.1) port 31515
* ALPN: curl offers h2,http/1.1
* (304) (OUT), TLS handshake, Client hello (1):
* (304) (IN), TLS handshake, Server hello (2):
* (304) (IN), TLS handshake, Unknown (8):
* (304) (IN), TLS handshake, Certificate (11):
* (304) (IN), TLS handshake, CERT verify (15):
* (304) (IN), TLS handshake, Finished (20):
* (304) (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / AEAD-AES256-GCM-SHA384 / [blank] / UNDEF
* ALPN: server did not agree on a protocol. Uses default.
* Server certificate:
*  subject: C=US; O=company; CN=127.0.0.1; OU=engineering
*  start date: Sep  8 19:37:55 2025 GMT
*  expire date: Sep  8 19:37:55 2026 GMT
*  issuer: C=US; O=company; CN=127.0.0.1; OU=engineering
*  SSL certificate verify result: self signed certificate (18), continuing anyway.
* using HTTP/1.x
> GET / HTTP/1.1
> Host: 127.0.0.1:31515
> User-Agent: curl/8.7.1
> Accept: */*
> 
* Request completely sent off
< HTTP/1.1 200 OK
< Date: Tue, 20 Jan 2026 02:05:51 GMT
< Connection: Keep-Alive
< Pragma: no-cache
< Content-Security-Policy: default-src 'self' *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:* https:
//127.0.0.1:*; style-src 'self' 'unsafe-inline' *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:* http
s://127.0.0.1:*; script-src 'self' 'unsafe-inline' 'unsafe-eval' *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https:/
/localhost:* https://127.0.0.1:*; img-src 'self' blob *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:
* https://127.0.0.1:* data:; font-src 'self' *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:* https:/
/127.0.0.1:* data:; frame-ancestors 'self' *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:* https://1
27.0.0.1:*; frame-src 'self' https://www.getfeedback.com *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localho
st:* https://127.0.0.1:*; connect-src 'self' blob: *.mathworks.com:* *.thingspeak.com:* thingspeak.com:* *.matlab.com:* https://localhost:* h
ttps://127.0.0.1:* wss://localhost:* wss://127.0.0.1:*
< Strict-Transport-Security: max-age=31536000; includeSubDomains
< X-XSS-Protection: 1; mode=block
< Expires: Wed, 21 Oct 2015 07:28:00 GMT
< Referrer-Policy: strict-origin
< Content-Length: 211
< X-Content-Type-Options: nosniff
< ETag: "1459445420211"
< Last-Modified: Thu, 31 Mar 2016 17:30:20 GMT
< Content-Type: text/html
< Accept-Ranges: bytes
< Cache-Control: no-cache, no-store, must-revalidate
< X-Frame-Options: sameorigin
< Set-Cookie: JSESSIONID2=NsEB6LqS8aPtNZS7; Path=/; HttpOnly; Secure; SameSite=None
< 
<!doctype html>
<html>
<head>
    <title>connector service</title>
        <link href="/css/connector.css" rel="stylesheet" type="text/css" />
</head>
<body>
        <h1>The connector service is running.</h1>
</body>
</html>
* Connection #0 to host 127.0.0.1 left intact

To Reproduce

1. open neovim in a Matlab project folder (root of git repository)
2. open a .m file
3. :LspInfo shows server attached to buffer but no serverInfo.version
4. try to use LSP features, they don't work
5. check :LspLog and see connection timeout errors

Expected behavior
I expect the language server to connect and for :LspInfo to show a server version. I expect the basic language server functions to work. I understand that hover is not currently supported, but there is no completion suggestion and

Useful Information

• MATLAB Version: R2024a (24.1.0.2537033) 64-bit (maca64)
• Operating System: MacOS 26.2 on M2 Pro
• Editor: vim v0.12.0-dev
• matlab-language-server v1.3.8 #92c424b
• node 25.3.0

[nickcounts]

Attaching my init.lua config for additional context. Not sure what else is helpful ¯_(ツ)_/¯

-- MATLAB LSP
---@type vim.lsp.Config
vim.lsp.config("matlab_ls", {
  -- cmd = {'matlab-language-server', '--socket 31515'},
  cmd = { 'matlab-language-server', '--stdio' },
  filetypes = { 'matlab' },
  root_dir = function(bufnr, on_dir)
    local root_dir = vim.fs.root(bufnr, '.git')
    on_dir(root_dir or vim.fn.getcwd())
  end,
  settings = {
    MATLAB = {
      indexWorkspace = false,
      matlabConnectionTiming = 'onStart',
      prewarmGraphics = false,
      telemetry = false,
      installPath = '/Applications/MATLAB_R2024a.app', -- NOTE: Set this to your MATLAB installation path.
    },
  },
})

vim.lsp.enable("matlab_ls")

Included the commented-out attempt at using the socket. See failure log attached above