nteract/papermill

`--help-notebook` does not respect `--kernel` CLI argument

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#905 opened on Aug 10, 2026

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bughelp wanted

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Description

🐛 Bug

It seems that papermill --help-notebook ignores the --kernel option. Papermill version 2.7.0

$ papermill --help-notebook --kernel uvkernel papermill-test.ipynb
Usage: papermill [OPTIONS] NOTEBOOK_PATH [OUTPUT_PATH]

Parameters inferred for notebook 'papermill-test.ipynb':
Traceback (most recent call last):
  File "/Users/voipiti/Documents/repos/minerva-optimization/ui-job-launch/python-papermill-test-script/.venv/bin/papermill", line 10, in <module>
    sys.exit(papermill())
             ~~~~~~~~~^^
<cut>
  File "<censored>/python-papermill-test-script/.venv/lib/python3.14/site-packages/papermill/utils.py", line 52, in nb_kernel_name
    raise ValueError("No kernel name found in notebook and no override provided.")
ValueError: No kernel name found in notebook and no override provided.

Omitting --help-notebook but retaining the --kernel uvkernel option results in successful run of Papermill and produces the expected output.

jupyter kernelspec list shows that uvkernel is a recognized kernel.

Contributor guide

Research direction
Investigate the CLI code path for the ` help notebook` option. Check how it extracts notebook parameters and why the ` kernel` argument is not forwarded. Trace the function calls from the command line entry point to where the kernel name is fetched.
Tech stack
python
Domain
cli
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitPython
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75