Using IPython magic commend "%reset" breaks the debugger

[nbelakovski]

Applies To

• Notebooks (.ipynb files)
• Interactive Window and/or Cell Scripts (.py files with #%% markers)

What happened?

1. Create a python file with a cell via # %% and add some statements and a breakpoint via the sidebar
2. Run "Debug cell" just to make sure everything runs as normal. Close the interactive window after this.
3. Add #!%reset -f somewhere in the cell
4. Run "Debug cell"

The cell will run twice and it will hit the breakpoint both times, but try running "Debug cell" after that and it won't hit the breakpoint. Even if you restart the kernel, it doesn't hit the breakpoint. If you close the tab with the interactive window now you can run "Debug cell" again, although you get the same behavior.

The same behavior happens with #!%reset -s (soft reset). It doesn't happen if any if in, out, array, or dhist or any combination thereof is provided, but then it doesn't quite do the reset that I'm looking for.

VS Code Version

Version: 1.101.1 (Universal) Commit: 18e3a1ec544e6907be1e944a94c496e302073435 Date: 2025-06-18T13:35:12.605Z Electron: 35.5.1 ElectronBuildId: 11727614 Chromium: 134.0.6998.205 Node.js: 22.15.1 V8: 13.4.114.21-electron.0 OS: Darwin arm64 23.5.0

Jupyter Extension Version

2025.5.0

Jupyter logs

Coding Language and Runtime Version

python 3.12.4

Language Extension Version (if applicable)

No response

Anaconda Version (if applicable)

No response

Running Jupyter locally or remotely?

Local

[nbelakovski]

I also tried with #%!reset_selective -f .* since that seemed to be a workaround for another issue (#8921), but no luck unfortunately, it had the same behavior as described above.

[nbelakovski]

Good news! I've found a workaround:

#!%reset_selective -f ^(?!(debugpy|get_ipython|os|trace_this_thread)$).*$

What I noticed from #!%who_ls is that there were 4 variables other than the ones I defined, the ones you see above. By creating this regex to make sure those aren't reset, we can reset all the other variables in the user namespace. It seems to work fine even if debugpy and trace_this_thread are excluded from the list and reset, but I think it doesn't hurt to leave those in there.

I'm not quite sure how those variables get into the user namespace, maybe there's a more permanent solution that involves keeping them out of there? And then folks could use "%reset" freely without having to get confused and find this workaround.