Issue with 'save and export notebook as'

[gwsullivan2001]

Description

The "save and export notebook as" is not functioning with the latest release

Reproduce

with an open notebook file

1. Go to 'file'
2. Click on 'save and export notebook as'
3. Scroll down to 'HTML'

A white blank window shows up. Previously a pop up window would also show up letting you name and navigate
where to save the exported file. Currently nothin shows up and no file is written anywhere

Expected behavior

A file window normally pops up on the Mac allowing me to name and save the exported file

using nbconvert in the terminal window in the jupyterlab desktop app does work!

Context

• Operating System and version: Tahoe 26.6.2
• JupyterLab-Desktop version: 4.6.3.1
• Installer: dmg

Troubleshoot Output

Paste the output from running `jupyter troubleshoot` from the terminal inside of JupyterLab Desktop here.
You may want to sanitize the paths in the output.

Browser Output (required for interface issues after loading)

Paste the output from the DevTools JavaScript console here, if applicable.

Logs (required for issues with loading, server and startup)

Paste the logs from the `main.log` file here (optionally also from `renderer.log`).

[notluquis]

Thanks for the clear report, I was able to trace this to the navigation guard introduced in 4.6.3-1.

JupyterLab opens the nbconvert export URL in a same-origin popup. LabView allows that popup, but its newly created webContents is then treated as unclaimed by the application-wide deny-by-default guard, so its initial navigation is cancelled. That leaves the blank window and prevents Electron's normal download/save flow from starting.

I opened draft PR #1135 to claim the allowed child and apply LabView's existing navigation policy to it. It has focused integration coverage for the initial export navigation, subsequent off-origin navigation, redirects into auth, and nested popups; CI is now running.

@krassowski once the PR has been reviewed and CI is green, could you advise whether this warrants a patch release? It is a regression in the current 4.6.3-1 release affecting notebook export.

I will post back here when the fix is merged and a release decision is confirmed.

[gwsullivan2001]

Thanks so much for the rapid triage on this issue. Any estimate on when the fix might role into a new release? I'm starting a course in scientific programming today and would like to give the students an estimate on when this export to html feature might be back into the menu as opposed to using nbconvert in the terminal. Thanks again!