Jupyter extension fails with "invalid WIN32 path characters" error

[bigeorgiev]

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Jupyter Extension Path Bug on Windows

Issue: Jupyter extension fails with "invalid WIN32 path characters" error

Environment:

• Cursor: 1.99.3
• Jupyter Extension: 2025.3.0 and 2024.11.0 (both affected)
• OS: Windows 11/10
• Python: 3.13.7

Error:

Error: /c:/Users/~/AppData/Roaming/Cursor/User/globalStorage/ms-toolsai.jupyter/version-2025.3.0/jupyter/kernels contains invalid WIN32 path characters.

Root Cause:
Extension uses Unix-style path normalization (/c:/Users/~/...) instead of Windows native paths (C:\Users\GEB\...)

Steps to Reproduce:

1. Install Cursor on Windows
2. Install Jupyter extension
3. Try to open any .ipynb file
4. Click "Select Kernel"
5. Error occurs

Suggested Fix:
The Jupyter extension should:

1. Use Windows-native path format (C:\Users\...) on Windows
2. Avoid Unix-style path normalization (/c:/Users/...) on Windows
3. Properly handle Windows path construction in the runtime directory setup

Workarounds Used:

• Set HOME environment variable (doesn't help)
• Restarted computer (doesn't help)
• Downgraded extension versions (doesn't help)
• Currently using JupyterLab as alternative