# JupyterLab Desktop - Cannot launch session

**URL:** <https://discourse.jupyter.org/t/jupyterlab-desktop-cannot-launch-session/36034>\
**Category:** JupyterLab\
**Tags:** help-wanted\
**Created:** [June 11, 2025, 10:12pm UTC](https://discourse.jupyter.org/t/jupyterlab-desktop-cannot-launch-session/36034 "2025-06-11T22:12:10Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![SeadonWare](https://avatars.discourse-cdn.com/v4/letter/s/977dab/32.png) [@SeadonWare](https://discourse.jupyter.org/u/SeadonWare)\
**Post date:** [June 11, 2025, 10:12pm UTC](https://discourse.jupyter.org/t/jupyterlab-desktop-cannot-launch-session/36034/1 "2025-06-11T22:12:10Z")

</div>

Currently attempting to use JupyterLab desktop. I was able to use JuypterLab Browser launching via Python (py -m juypterlab). However, with the desktop version I recieve the following error JavaScript error:

[Window Title]

Error

[Main Instruction]

A JavaScript error occurred in the main process

[Content]

Uncaught Exception:

TypeError: Cannot read properties of undefined (reading ‘uiMode’)

```
at IpcMainImpl.<anonymous> (C:\JupyterLab\resources\app.asar\build\out\main\sessionwindow\sessionwindow.js:631:47)

at IpcMainImpl.emit (node:events:514:28)

at WebContents.<anonymous> (node:electron/js2c/browser_init:2:88262)

at WebContents.emit (node:events:514:28)

```

[OK]

This occurs when attempting to launch either a new notebook or new session. Within JuypterLab, it’s listed as a “Failed to create session!” error. I am attempting to use Python 3.13 as the Python environment.

Steps tried:

- Restarting my machine (multiple times)
- Using different version of Python for environment (3.9)
- Uninstalling and reinstalling JuypterLab (restarted after some, not after others)
- Using older version of JuypterLab
- Clearing and rebuilt Kernel specs
- Cleared desktop app configs
- Tried running JupyerLab as admin and disabling GPU
- Attempted to open dev tools (wouldn’t open)
- Nothing in windows event viewer

Any help would be appreciated. Let me know if you need more information.