Exception when trying serve hidden file or directory

[andrii-i]

Issue jupyterlab/jupyterlab#17825 in JupyterLab describes an exception when trying serve hidden file or directory.

The refusal to serve hidden file or directory should probably be handled by jupyter-server without throwing Uncaught exception GET.

Copying the original content below as a part of Jupyter Frontends triaging group work.

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Description

I use a pipx-installed JupyterLab. While working on a notebook that uses the pygithub package I occasionally see these errors on the terminal where the jupyter-lab command is running ¹:

[W 2025-08-27 15:15:09.266 ServerApp] 404 GET /api/contents/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/github/Requester.py?content=0&hash=0&1756300509261 (b70af31f03de4096ad3d70ccdbdbc4e9@127.0.0.1) 0.49ms referer=http://localhost:8888/lab/tree/arrow/stats/gh-arrow.ipynb
[I 2025-08-27 15:15:09.266 ServerApp] Refusing to serve hidden file or directory '/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/github/Requester.py', via 404 Error
[E 2025-08-27 15:15:09.266 ServerApp] Uncaught exception GET /api/contents/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/github/Requester.py?content=0&hash=0&1756300509261 (127.0.0.1)
    HTTPServerRequest(protocol='http', host='localhost:8888', method='GET', uri='/api/contents/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/github/Requester.py?content=0&hash=0&1756300509261', version='HTTP/1.1', remote_ip='127.0.0.1')
    Traceback (most recent call last):
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/handlers.py", line 156, in get
        model = await ensure_async(
                ^^^^^^^^^^^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_core/utils/__init__.py", line 197, in ensure_async
        result = await obj
                 ^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/filemanager.py", line 928, in get
        model = await self._file_model(
                ^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/filemanager.py", line 829, in _file_model
        model = self._base_model(path)
                ^^^^^^^^^^^^^^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/filemanager.py", line 237, in _base_model
        raise web.HTTPError(404, four_o_four)
    tornado.web.HTTPError: HTTP 404: Not Found (file or directory does not exist: '.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/github/Requester.py')
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/tornado/web.py", line 1848, in _execute
        result = await result
                 ^^^^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/auth/decorator.py", line 73, in inner
        return await out
               ^^^^^^^^^
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/handlers.py", line 182, in get
        await self._finish_error(
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/jupyter_server/services/contents/handlers.py", line 114, in _finish_error
        self.write(message)
      File "/home/antoine/.local/pipx/venvs/jupyterlab/lib/python3.12/site-packages/tornado/web.py", line 964, in write
        raise RuntimeError("Cannot write() after finish()")
    RuntimeError: Cannot write() after finish()

Note that github/Requester.py is typically a module from pygithub. I have no idea why JupyterLab is trying to fetch it using HTTP.

Reproduce

1. Install jupyterlab and pygithub using pipx:

$ pipx install jupyterlab --include-deps
$ pipx inject jupyterlab pygithub

2. Start jupyter-lab in a terminal
3. Create a new ipykernel-based notebook
4. Paste the following code in a cell:

from github import Auth, Github
token = Auth.Token('xxx')  # intentionally invalid token
g = Github(auth=token)
repo = g.get_repo('apache/arrow')

5. Run the cell

Expected behavior

Context

• Operating System and version: Ubuntu 24.04
• Browser and version: Firefox 142.0
• JupyterLab version: 4.4.7 (installed using pipx)

Footnotes

1. Not the JupyterLab error console, as my original wording might have confusingly implied ↩