Plugin not respecting $PATH? MCP can't call npx/node

[Datamance]

Which version of LM Studio?
Example: LM Studio 0.3.22

Which operating system?
Mac

What is the bug?
Try adding something like playwright to mcp.json

...
    "context7": {
      "url": "https://mcp.context7.com/mcp"
    },
    "deepwiki": {
      "url": "https://mcp.deepwiki.com/mcp"
    },
    "playwright": {
      "command": "npx",
      "args": [
        "@playwright/mcp@latest"
      ]
    }
...

And the plugin process will fail to start, due to [Plugin(mcp/playwright)] stderr: env: node: No such file or directory. This happens even when I open LMStudio from the command line.

I manage my node installation with mise, so there's quite a few shimmed paths that might be confusing LM Studio as to where npx/node live... Just a guess.

I can add streaming http MCP sources just fine.

Logs

Developer Logs
2025-08-07 11:47:22 [DEBUG]
[Client=plugin:installed:lmstudio/js-code-sandbox] Client created.
2025-08-07 11:47:22 [INFO]
[Plugin(lmstudio/js-code-sandbox)] stdout: [Tools Prvdr.] Register with LM Studio
2025-08-07 11:47:23 [DEBUG]
[Client=plugin:installed:lmstudio/js-code-sandbox][Endpoint=setToolsProvider] Registering tools provider.
2025-08-07 12:06:32 [DEBUG]
[Client=plugin:installed:lmstudio/js-code-sandbox] Client created.
2025-08-07 12:06:32 [INFO]
[Plugin(lmstudio/js-code-sandbox)] stdout: [Tools Prvdr.] Register with LM Studio
2025-08-07 12:06:32 [DEBUG]
[Client=plugin:installed:lmstudio/js-code-sandbox][Endpoint=setToolsProvider] Registering tools provider.
2025-08-07 12:07:25 [DEBUG]
[Client=plugin:installed:mcp/playwright] Client created.
2025-08-07 12:07:25 [ERROR]
[Plugin(mcp/playwright)] stderr: env: node: No such file or directory
2025-08-07 12:07:25 [ERROR]
[Plugin(mcp/playwright)] stderr: Error in LM Studio MCP bridge process: _0xb7292 [McpError]: MCP error -32000: Connection closed
at _0x589280._onclose (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:827846)
at .onclose (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:826574)
at ChildProcess. (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:801737)
at ChildProcess.emit (node:events:519:28)
at maybeClose (node:internal/child_process:1105:16)
at ChildProcess._handle.onexit (node:internal/child_process:305:5) {
code: -32000,
data: undefined
}
2025-08-07 12:07:25 [ERROR]
[Plugin(mcp/playwright)] stderr: _0xb7292 [McpError]: MCP error -32000: Connection closed
at _0x589280._onclose (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:827846)
at .onclose (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:826574)
at ChildProcess. (/Applications/LM Studio.app/Contents/Resources/app/.webpack/lib/mcpbridgeworker.js:1:801737)
at ChildProcess.emit (node:events:519:28)
at maybeClose (node:internal/child_process:1105:16)
at ChildProcess._handle.onexit (node:internal/child_process:305:5) {
code: -32000,
data: undefined
}
2025-08-07 12:07:25 [DEBUG]
[Client=plugin:installed:mcp/playwright] Client disconnected.

To Reproduce

1. add playwright to mcp config:

...
"playwright": {
      "command": "npx",
      "args": [
        "@playwright/mcp@latest"
      ]
    }
...

[Datamance]

Confirmed that when I run ln -s "$(which node)" /usr/local/bin/node, the MCP server is able to start up. So something is up with PATH loading/searching.

[tonyarnold]

I'm seeing the same for tools installed by brew.

[renesugar]

I tried installing mcp/docs-mcp-server as a plugin running on Ubuntu Linux.

'node_modules/psl/dist/psl.mjs' is inside the node_modules folder in the AppImage but it is searching the system instead of the node_modules folder inside the AppImage.

If I install the node psl package, it contains a "cjs" file instead of an "mjs" file and still doesn't find the file it is looking for.

patchelf --print-rpath ./LM-Studio-0.3.23-3-x64.AppImage

If you extract the files in the AppImage, you can see the node_modules directory has the file it is looking for but it is not finding it.

chmod u+x LM_Studio-*.AppImage
./LM_Studio-*.AppImage --appimage-extract

2025-08-27 16:49:37 [ERROR]
 [Plugin(mcp/docs-mcp-server)] stderr: node:internal/modules/run_main:107
    triggerUncaughtException(
    ^

Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/home/renes/.npm/_npx/226752580240d182/node_modules/psl/dist/psl.mjs' imported from /home/renes/.npm/_npx/226752580240d182/node_modules/@arabold/docs-mcp-server/dist/index.js
Did you mean to import "psl/dist/psl.cjs"?
    at finalizeResolution (node:internal/modules/esm/resolve:274:11)
    at moduleResolve (node:internal/modules/esm/resolve:864:10)
    at defaultResolve (node:internal/modules/esm/resolve:990:11)
    at #cachedDefaultResolve (node:internal/modules/esm/loader:749:20)
    at ModuleLoader.resolve (node:internal/modules/esm/loader:726:38)
    at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:312:38)
    at #link (node:internal/modules/esm/module_job:208:49) {
  code: 'ERR_MODULE_NOT_FOUND',
  url: 'file:///home/renes/.npm/_npx/226752580240d182/node_modules/psl/dist/psl.mjs'
}

[Datamance]

I'm seeing the same for tools installed by brew.

I would bet. If it's only searching hardcoded system paths then it'll miss whatever corner of the file system your package manager uses.

I tried installing mcp/docs-mcp-server as a plugin running on Ubuntu Linux.

That sounds like a slightly different issue since it has to do with (internal) plugins, which are technically distinct (in terms of interface) from externally defined MCP services. IMO you should crack open a bug for that one

[CelesteGH]

Same here using mise on windows.

[Eric2XU]

this "might" help some others, I had this same issue:

stderr: env: node: No such file or directory

I too used brew on a mac and it was installed to /opt/homebrew/bin/npx BUT was properly in path and that didnt seem to matter. I also had a older version of node in /usr/local/bin/ although that didnt end up mattering (I did remove it and setup symbolic links which also didnt fix it).

Then I figured it out (at least my problem). I use chsh to change my shell from zsh to pwsh, specificly /usr/local/bin/pwsh

LM Studio must use the default shell assigned to the identity and it was expecting zsh not pwsh so it couldnt read the path var (I guess).

This did the trick for me:
chsh -s /bin/zsh

I use iterm2 anyways so it was easy enough to have my default profile within the iterm2 run pwsh which doesnt change it for LM Studio.

I see this issue happens on windows too, maybe this might provide some insight as to when the app fails to pull path correctly.

Good luck out there. Funny enough, this is OG thought, ai didnt help me with this one lol...

[alfureu]

same problem with npm installed with nvm.sh. The AppImage cannot see/execute the command

[SurgeMonkeyAU]

Ran into this same issue on W11 v10.0.26200. Turns out my issue was caused by the App Launcher i was using which didn't inherit the updated system paths after nodejs was installed. Running LM Studio directly resulted in it inheriting the correct paths. Was able to see the environment variables loaded using System Informer.

[Stratiev]

Encountered the same problem in Windows. After some investigation of running powershell scripts as custom mcps, exporting env vars and writing them to a file I realized that I could not get lm studio to use my system or shell env vars (and by extension PATH). So I made this hack:

{
    "mcpServers": {
        "filesystem": {
            "command": "powershell",
            "args": [
                "-File",
                "C:\\Users\\path\\to\\custom\\script.ps1"
            ]
        }
    }
}

where the script runs the mcp of interest with a hardcoded path modification. Hacky and stupid but it works and makes sense unlike any of the other solutions I found on the web or recommended by llms.

$env:PATH = 'C:\Program Files\nodejs;' + $env:PATH
npx -y @modelcontextprotocol/server-filesystem C:\\Users\\username 

Anyways, apologies for the terrible hack but I hope it helps somebody.