nteract/papermill

kernel_name argument of papermill.execute seems to have no effect.

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#856 opened on Dec 17, 2025

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bughelp wanted

Description

🐛 Bug

The kernel_name argument of papermill.execute seems to have no effect. The executing notebook uses the Jupyter kernel specified in the original notebook's metatdata. Using papermill v2.6.0. Or at least the display_name in the metadata is unchanged, this is what jupyter hub uses to display the name of the kernal being used.

Something along the lines of this function should fix this:

import nbformat as nbf

def change_notebook_kernel(input_path, output_path, kernel):
    """
    Change a Jupyter Notebook's kernel.

    Parameters
    ----------
    input_path: str
        Path to the input notebook.
    output_path: str
        Path to the output notebook.
    kernel: str
        Name of the kernel_name to change to.
    """
    notebook = nbf.read(input_path, as_version=4)
    notebook['metadata']['kernelspec']['name'] = kernel
    notebook['metadata']['kernelspec']['display_name'] = kernel
    nbf.write(notebook, output_path)

Contributor guide

Tech stack
python
Domain
data
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
PythonpapermillJupyter notebooks
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75
Research direction
Investigate the execute function in papermill's core module (likely papermill/execute.py) to understand how kernel name is passed to the notebook execution. The fix should update the notebook's metadata kernelspec name and display name after execution, similar to the provided snippet. Also check if there are existing tests for kernel specification.