Jupyter lab 4.0.6 error on startup about yarn configuration and worker_threads

JupyterLab
1

I’m getting the following error when starting jupyter lab:

% Fail to get yarn configuration. internal/modules/cjs/loader.js:582
    throw err;
    ^

Error: Cannot find module 'worker_threads'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:580:15)
    at Function.Module._load (internal/modules/cjs/loader.js:506:25)
    at Module.require (internal/modules/cjs/loader.js:636:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at /misc/working/projects/pysicr/test_deployment/lib/python3.9/site-packages/jupyterlab/staging/yarn.js:423:2576
    at Object.<anonymous> (/misc/working/projects/pysicr/test_deployment/lib/python3.9/site-packages/jupyterlab/staging/yarn.js:743:8770)
    at Module._compile (internal/modules/cjs/loader.js:688:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:699:10)
    at Module.load (internal/modules/cjs/loader.js:598:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:537:12)

This is not fatal. Things seem to be working fine anyway, but I have not tested a lot of stuff.

Jupyter is installed in a vitualenv with python 3.9 in centos 7.

The only changes I had to make during the installation was to downgrade urllib3 to <2.0, because the default installed as a requirement was giving other errors.

Thanks,
JP

1 Like
2

Thanks for the report. What version of nodejs is this against?

If this is a “long term” build that will be frequently restarted, one can also configure the startup to avoid all nodejs-based things, which generally are neither useful or interesting for 4.x (which generally prefers pre-built extensions):

https://jupyterlab.readthedocs.io/en/stable/user/directories.html#disabling-rebuild-checks

e.g. in jupyter_server_config.json:

{
  "LabApp": {
    "tornado_settings": {
      "page_config_data": {
        "buildCheck": false,
        "buildAvailable": false,
      }
    }
  }
}

This can help both startup time and stability.

3

Are you saying these errors are not related to the operation of Jupyter server or lab, and it’s something about the build check on startup?

My use case is that I have several users and I try to maintain a common stable environment for them. But people are starting/restarting Jupyter all the time. If this error is harmless, then I’d be happy to find a way to suppress it / prevent it.

I will try your suggestions.

4

Similar issue as jpcarm

Fail to get yarn configuration. internal/modules/cjs/loader.js:638
    throw err;
    ^

Error: Cannot find module 'worker_threads'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at /home/luca/mambaforge/lib/python3.10/site-packages/jupyterlab/staging/yarn.js:423:2576
    at Object.<anonymous> (/home/luca/mambaforge/lib/python3.10/site-packages/jupyterlab/staging/yarn.js:743:8770)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)

This message is no longer showing after updating node.js .
The easiest way to update on my system (linux mint) was to use NVM.
install node.js on Linux Mint

using

Step 2: Install Node.js via NVM

Hope it helps

1 Like
5

Hi,

I am beginning with Jupyter lab (running on Windows) and I have an error which seems similar to jpcaram.

May someone explain what does it mean and how to fix it if required ?

image
image2966×1714 362 KB

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C:\Users\paulb>jupyter lab
Fail to get yarn configuration.
C:\Users\paulb\AppData\Local\Programs\Python\Python313\Lib\site packages\jupyterlab\staging\yarn.js:4
(()=>{var Qge=Object.create;var AS=Object.defineProperty;var
bge=Object.getOwnPropertyDescriptor;var Sge=Object.getOwnPropertyNames;var vge=Object.getPrototypeOf,xge=Object.prototype.hasOwnProperty;var J=(r=>typeof require<“u”?require:typeof Proxy<“u”?new Proxy(r,{get:(e,t)=>(typeof require<“u”?require:e)[t]}):r)(function(r){if(typeof require<“u”)return require.apply(this,arguments);throw new Error(‘Dynamic require of "’+r+‘" is not supported’)});var Pge=(r,e)=>()=>(r&&(e=r(r=0)),e);var w=(r,e)=>()=>(e||r((e={exports:{}}).exports,e),e.exports),ut=(r,e)=>{for(var t in e)AS(r,t,{get:e[t],enumerable:!0})},Dge=(r,e,t,i)=>{if(e&&typeof e==“object”||typeof e==“function”)for(let n of Sge(e))!xge.call(r,n)&&n!==t&&AS(r,n,{get:()=>e[n],enumerable:!(i=bge(e,n))||i.enumerable});return r};var Pe=(r,e,t)=>(t=r!=null?Qge(vge(r)):{},Dge(e||!r||!r.__esModule?AS(t,“default”,{value:r,enumerable:!0}):t,r));var QK=w((GXe,BK)=>

SyntaxError: Unexpected token {
at createScript (vm.js:56:10)
at Object.runInThisContext (vm.js:97:10)
at Module._compile (module.js:549:28)
at Object.Module._extensions..js (module.js:586:10)
at Module.load (module.js:494:32)
at tryModuleLoad (module.js:453:12)
at Function.Module._load (module.js:445:3)
at Module.runMain (module.js:611:10)
at run (bootstrap_node.js:387:7)
at startup (bootstrap_node.js:153:9)

[I 2025-06-15 15:26:24.097 ServerApp] jupyter_lsp | extension was successfully linked.
[I 2025-06-15 15:26:24.103 ServerApp] jupyter_server_terminals | extension was successfully linked.
[I 2025-06-15 15:26:24.110 ServerApp] jupyterlab | extension was successfully linked.
[I 2025-06-15 15:26:24.552 ServerApp] notebook_shim | extension was successfully linked.
[I 2025-06-15 15:26:24.599 ServerApp] notebook_shim | extension was successfully loaded.
[I 2025-06-15 15:26:24.601 ServerApp] jupyter_lsp | extension was successfully loaded.
[I 2025-06-15 15:26:24.601 ServerApp] jupyter_server_terminals | extension was successfully loaded.
[I 2025-06-15 15:26:24.605 LabApp] JupyterLab extension loaded from C:\Users\paulb\AppData\Local\Programs\Python\Python313\Lib\site-packages\jupyterlab
[I 2025-06-15 15:26:24.605 LabApp] JupyterLab application directory is C:\Users\paulb\AppData\Local\Programs\Python\Python313\share\jupyter\lab
[I 2025-06-15 15:26:24.606 LabApp] Extension Manager is ‘pypi’.
[I 2025-06-15 15:26:25.048 ServerApp] jupyterlab | extension was successfully loaded.
[I 2025-06-15 15:26:25.050 ServerApp] Serving notebooks from local directory: C:\Users\paulb
[I 2025-06-15 15:26:25.050 ServerApp] Jupyter Server 2.16.0 is running at:
[I 2025-06-15 15:26:25.050 ServerApp] http://localhost:8888/lab?token=1bd46ce1d22abb4bf003d14d857a9d4ee0f7949656b9f343
[I 2025-06-15 15:26:25.051 ServerApp] http://127.0.0.1:8888/lab?token=1bd46ce1d22abb4bf003d14d857a9d4ee0f7949656b9f343
[I 2025-06-15 15:26:25.051 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 2025-06-15 15:26:25.087 ServerApp]

To access the server, open this file in a browser:
    file:///C:/Users/paulb/AppData/Roaming/jupyter/runtime/jpserver-6532-open.html
Or copy and paste one of these URLs:
    http://localhost:8888/lab?token=1bd46ce1d22abb4bf003d14d857a9d4ee0f7949656b9f343
    http://127.0.0.1:8888/lab?token=1bd46ce1d22abb4bf003d14d857a9d4ee0f7949656b9f343

[I 2025-06-15 15:26:25.221 ServerApp] Skipped non-installed server(s): bash-language-server, dockerfile-language-server-nodejs, javascript-typescript-langserver, jedi-language-server, julia-language-server, pyright, python-language-server, python-lsp-server, r-languageserver, sql-language-server, texlab, typescript-language-server, unified-language-server, vscode-css-languageserver-bin, vscode-html-languageserver-bin, vscode-json-languageserver-bin, yaml-language-server
[W 2025-06-15 15:26:28.113 LabApp] Could not determine jupyterlab build status without nodejs
[I 2025-06-15 15:26:29.264 ServerApp] Kernel started: a9383ec0-73c0-44ba-be4b-55a14f13d4bb
[I 2025-06-15 15:26:30.581 ServerApp] Connecting to kernel a9383ec0-73c0-44ba-be4b-55a14f13d4bb.
[I 2025-06-15 15:26:30.590 ServerApp] Connecting to kernel a9383ec0-73c0-44ba-be4b-55a14f13d4bb.
[W 2025-06-15 15:26:30.607 ServerApp] The websocket_ping_timeout (90000) cannot be longer than the websocket_ping_interval (30000).
Setting websocket_ping_timeout=30000
[I 2025-06-15 15:26:30.612 ServerApp] Connecting to kernel a9383ec0-73c0-44ba-be4b-55a14f13d4bb.

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