Could not determine npm prefix: [WinError 2] The system cannot find the file specified

[JulianSMoore]

I'm not a dev so I hope the following suffices to be useful:

Windows 10
IPython : 8.16.1
ipykernel : 6.25.2
ipywidgets : 8.1.1
jupyter_client : 8.4.0
jupyter_core : 5.4.0
jupyter_server : 2.8.0
jupyterlab : 4.0.7
nbclient : 0.8.0
nbconvert : 7.9.2
nbformat : 5.9.2
notebook : not installed
qtconsole : not installed
traitlets : 5.11.2

with jupyterlab-lsp==5.0.0 jupyter-lsp==2.2.0 python-lsp-server[all]

on startup, the console kept saying "Could not determine npm prefix: [WinError 2] The system cannot find the file specified"

It's not that npm is missing, it's because WIndows isn't Linux; see here

I resolved the problem for myself: in C:\Users\Julian\anaconda3\envs\PlainPY\Lib\site-packages\jupyter_lsp\types.py

In the class LanguageServerManagerAPI, change _npm_prefix to be

def _npm_prefix(self):
    try:
        return (
            subprocess.run(["npm.cmd", "prefix", "-g"], check=True, capture_output=True)
            .stdout.decode("utf-8")
            .strip()
        )
    except Exception as e:  # pragma: no cover
        self.log.warn(f"Could not determine npm prefix: {e}")

i.e. add ".cmd" to npm: the error wasn't saying the prefix couldn't be found, but rather it couldn't invoke npm in the first place,

Obviously that's not a fix for everyone, it's windows specific.

[krassowski]

I believe this should be solved with #955 which will be available in the next jupyter-lsp version.

[JulianSMoore]

Great. Strange that that issue wasn't obvious when I googled it first, but still -- great. Thx.

[waysbg]

**JulianSMoore ** commented

Tnks man, it helped, i mean adding .cmd to this part ....["npm.cmd", "prefix", "-g"].... as you have explained.
Tnks!!!

[WKQ9411]

Thanks for the solution, it really works!

[SpezialK71]

This fixed an annoying issue I'd been having for months.

Thanks!

[ygwang1]

Thanks!!!

[jtyoui]

Thanks!!!