Jupyter Notebook File Reading Fails with 400 Bad Request Error

Related issues:

• #400
• #869
• #930

To reproduce the issue, please see the attached files, which are also summarized below.

• [20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.ipynb

](https://gist.github.com/stharrold/612feda6182e6d2e2c61a2d5f34ad6ab) Example Jupyter (IPython) notebook that reproduces the API Error 400 from a generated plot/graph/image that has invalid base64 data.

• 20250504T093000Z_Claude-Code_Terminal-Output.txt

Terminal output from instructing Claude Code to read the Jupyter notebook, the subsequent API Error 400, and inability to exit error.

• 20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.html

HTML export of Jupyter notebook for testing.

The impact of this issue is that the scientific, research, and data science communities extensively use Jupyter (IPython) notebooks with embedded images for interactive development and as self-documenting project workflows.

Enabling Claude Code to seamlessly read and write these Jupyter notebooks would dramatically enhance productivity across these domains.

Thank you so much your work on this impactful tool!

Excerpt from 20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.ipynb

In [1]:
import matplotlib.pyplot as plt
%matplotlib inline

In [2]:
fig = plt.figure()
ax0 = fig.add_subplot(111)
plt.show(fig)

Excerpt from 20250504T093000Z_Claude-Code_Terminal-Output.txt

$ claude
(...)
> read 20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.ipynb

⏺ I'll read the Jupyter notebook file for you.

⏺ Read(20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.ipynb)…
  ⎿  Error: File is a Jupyter Notebook. Use the NotebookRead to read this file.

⏺ I need to use the NotebookRead tool for Jupyter notebook files:

⏺ Read Notebook(20250504T093000Z_Claude-Code_Issue-Reproduce-400-Error-From-Ipynb-Base64-Image.ipynb)…
  ⎿  Read 3 cells
  ⎿  API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.4.content.0.tool_result.content.1.image.source.base64: invalid base64 data"}}

> recover
  ⎿  API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.4.content.0.tool_result.content.1.image.source.base64: invalid base64 data"}}

The fix will go out in v1.0.4.

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