Sage: problem launching a Jupyter session

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I followed the installation instructions to the tee and running sage in the shell indeed gives a working Sage interactive command line session. But I could not get sage -n jupyter to work; here are the logs:

(sage) root@codespaces-b4d8c4:/workspaces/Self-Study# sage -n jupyter ┌────────────────────────────────────────────────────────────────────┐ │ SageMath version 10.7, Release Date: 2025-08-09 │ │ Using Python 3.12.12. Type "help()" for help. │ └────────────────────────────────────────────────────────────────────┘ Please wait while the Sage Jupyter Notebook server starts... /root/conda/envs/sage/lib/python3.12/site-packages/tornado/ioloop.py:271: DeprecationWarning: There is no current event loop loop = asyncio.get_event_loop() /root/conda/envs/sage/lib/python3.12/site-packages/traitlets/traitlets.py:3913: DeprecationWarning: Keyword `trait` is deprecated in traitlets 5.0, use `value_trait` instead warn( /root/conda/envs/sage/lib/python3.12/site-packages/traitlets/traitlets.py:3615: DeprecationWarning: Traits should be given as instances, not types (for example, `Int()`, not `Int`). Passing types is deprecated in traitlets 4.1. super().__init__(trait=trait, default_value=default_value, **kwargs) [I 2026-01-22 13:46:51.215 ServerApp] jupyter_lsp | extension was successfully linked. [I 2026-01-22 13:46:51.226 ServerApp] jupyter_server_terminals | extension was successfully linked. [I 2026-01-22 13:46:51.240 ServerApp] jupyterlab | extension was successfully linked. [I 2026-01-22 13:46:51.253 ServerApp] notebook | extension was successfully linked. [I 2026-01-22 13:46:51.262 ServerApp] Writing Jupyter server cookie secret to /root/.local/share/jupyter/runtime/jupyter_cookie_secret /root/conda/envs/sage/lib/python3.12/site-packages/traitlets/traitlets.py:1897: DeprecationWarning: ServerApp.token config is deprecated in jupyter-server 2.0. Use IdentityProvider.token return t.cast(Sentinel, self._get_trait_default_generator(names[0])(self)) [I 2026-01-22 13:46:51.294 ServerApp] notebook_shim | extension was successfully linked. [I 2026-01-22 13:46:51.343 ServerApp] notebook_shim | extension was successfully loaded. /root/conda/envs/sage/lib/python3.12/site-packages/jupyter_server/extension/manager.py:126: DeprecationWarning: A `_load_jupyter_server_extension` function was not found in <module 'jupyter_lsp' from '/root/conda/envs/sage/lib/python3.12/site-packages/jupyter_lsp/__init__.py'>. Instead, a `load_jupyter_server_extension` function was found and will be used for now. This function name will be deprecated in future releases of Jupyter Server. loader = get_loader(loc) [I 2026-01-22 13:46:51.355 ServerApp] jupyter_lsp | extension was successfully loaded. [I 2026-01-22 13:46:51.361 ServerApp] jupyter_server_terminals | extension was successfully loaded. [I 2026-01-22 13:46:51.395 LabApp] JupyterLab extension loaded from /root/conda/envs/sage/lib/python3.12/site-packages/jupyterlab [I 2026-01-22 13:46:51.395 LabApp] JupyterLab application directory is /root/conda/envs/sage/share/jupyter/lab [I 2026-01-22 13:46:51.395 LabApp] Extension Manager is 'pypi'. [I 2026-01-22 13:46:51.607 ServerApp] jupyterlab | extension was successfully loaded. [I 2026-01-22 13:46:51.622 ServerApp] notebook | extension was successfully loaded. [C 2026-01-22 13:46:51.625 ServerApp] Running as root is not recommended. Use --allow-root to bypass. (sage) root@codespaces-b4d8c4:/workspaces/Self-Study# sage -n --allow-root jupyter ┌────────────────────────────────────────────────────────────────────┐ │ SageMath version 10.7, Release Date: 2025-08-09 │ │ Using Python 3.12.12. Type "help()" for help. │ └────────────────────────────────────────────────────────────────────┘ Please wait while the Sage Jupyter Notebook server starts... [C 2026-01-22 13:47:21.550 ServerApp] No such file or directory: /workspaces/Self-Study/jupyter

For full reproducibility, I now note that this is done in a GitHub Codespace with a .devcontainer folder containing three files

1. .devcontainer.json
2. postCreateCommands
3. DockerFIle

I was going to post the code contents of each… but I can’t because my karma is insufficient to publish links? (Also, why does three backticks not seem to work to give a code block? I’ve never had this issue on any other site.)

One might question why I don’t just use FROM: sagemath/sagemath:latest. The answer is that this is the setup for my GitHub Codespace, which is primarily meant to be a TeX coding environment, but sometimes I might want to write some Julia/Sage/etc scripts.