papermill "parameters" cell not found / no tagged cell in CI

By Kaveh Alemi·Latchkey

papermill injects parameters by inserting a new cell immediately after the cell tagged parameters. If no cell carries that tag, papermill warns and inserts the injected cell at the top, which often runs before your defaults and breaks the notebook.

What this error means

papermill prints "Input notebook does not contain a cell with tag 'parameters'" and the run either ignores your overrides or fails because the injected cell ran in the wrong position.

Input notebook does not contain a cell with tag 'parameters'

Common causes

No cell is tagged "parameters"

papermill relies on the parameters cell tag to know where to inject overrides; without it, injection has no anchor.

The tag was lost or misspelled

An edit or a tool stripped the cell tags, or the tag is not exactly parameters, so papermill cannot find it.

How to fix it

Tag the defaults cell as parameters

1. In the notebook, add the cell tag parameters to the cell holding default values.
2. Keep that cell near the top, after imports.
3. Re-run papermill so overrides inject right after it.

papermill input.ipynb output.ipynb -p threshold 10

Verify the tag is preserved in source control

Confirm the parameters tag survives in the committed .ipynb (in cell metadata) so CI sees it.

How to prevent it

• Keep one defaults cell tagged exactly parameters.
• Place it after imports so injected overrides run before the rest.
• Review notebook metadata in diffs so the tag is not dropped.

Frequently asked questions

Related guides

References

• Python documentation
• pip documentation
• GitHub Actions documentation