Dear developer community,

Using ipykernel 6.30.0 starting a debug session in VSCode doesn't hit any breakpoints (and doesn't execute anything)

I started the debug session like this:

After a painful debugging session I discovered that downgrading ipykernel to the version 6.29.5 fixed the issue.

I'm using VSCode Version: 1.102.2
and the Jupyter Extension from Microsoft (ms-toolsai.jupyter) Version: 2025.6.0
My operating system: macOS Sequoia Version 15.5

Reproduction steps:

In a fresh folder

python -m venv .venv
source .venv/bin/activate
pip install jupyterlab
<start debugging session in an arbitrary .ipynb file using ".venv/bin/python" as the kernel>
<observe no breakpoints being hit>

I tested with python3.11 and python3.13

If you cannot reproduce the bug I'm happy to provide additional environment information.

Best regards,
Robin