# Jupyter Lab prevented from loading

**URL:** https://discourse.jupyter.org/t/jupyter-lab-prevented-from-loading/32352
**Category:** JupyterLab
**Tags:** help-wanted
**Created:** [February 1, 2025, 2:34pm UTC](https://discourse.jupyter.org/t/jupyter-lab-prevented-from-loading/32352 "2025-02-01T14:34:06Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![jaysun\_n](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/jaysun_n/32/13536_2.png) [@jaysun\_n](https://discourse.jupyter.org/u/jaysun_n)
#### Post date: [February 1, 2025, 2:34pm UTC](https://discourse.jupyter.org/t/jupyter-lab-prevented-from-loading/32352/1 "2025-02-01T14:34:06Z")

</div>

I am developing a Jupyter extension and I logged onto my Mac to continue development but suddenly my Jupyter and extension are malfunctioning. When I open the server with `jupyter lab` in the console I see [this log](https://pastebin.com/SQaCWtGn) where there are several errors and when the Firefox tab opens I am greeted with a 404 error screen. I didnt update my code or do anything between now and when I last had my install working. One thing I noticed that despite developing on JLab4, the jupyter version seems to think it was 3.6.8:

```auto
>> jupyter --version
Selected Jupyter core packages...
IPython : 8.31.0
/opt/anaconda3/envs/jlab4/bin/jupyter:10: DeprecationWarning: Parsing dates involving a day of month without a year specified is ambiguious
and fails to parse leap day. The default behavior will change in Python 3.15
to either always raise an exception or to use a different default year (TBD).
To avoid trouble, add a specific year to the input & format.
See https://github.com/python/cpython/issues/70647.
  sys.exit(main())
ipykernel : 6.29.5
ipywidgets : not installed
jupyter_client : 7.4.9
jupyter_core : 5.7.2
jupyter_server : 2.15.0
jupyterlab : 3.6.8
nbclient : 0.10.2
nbconvert : 7.16.5
nbformat : 5.10.4
notebook : 6.5.7
qtconsole : not installed
traitlets : 5.14.3

```

I reinstalled Jupyter through conda and now I am getting the proper version 4 but Im not sure why I was downgraded and whether that could have an impact on the reinstalled jupyter version.

```auto
>> jupyter --version      
Selected Jupyter core packages...
IPython : 8.31.0
/opt/anaconda3/envs/jlab4/bin/jupyter:10: DeprecationWarning: Parsing dates involving a day of month without a year specified is ambiguious
and fails to parse leap day. The default behavior will change in Python 3.15
to either always raise an exception or to use a different default year (TBD).
To avoid trouble, add a specific year to the input & format.
See https://github.com/python/cpython/issues/70647.
  sys.exit(main())
ipykernel : 6.29.5
ipywidgets : not installed
jupyter_client : 7.4.9
jupyter_core : 5.7.2
jupyter_server : 2.15.0
jupyterlab : 4.3.5
nbclient : 0.10.2
nbconvert : 7.16.5
nbformat : 5.10.4
notebook : 6.5.7
qtconsole : not installed
traitlets : 5.14.3

```

Any help debugging why my install suddenly isnt working would be greatly appreciated