Thomas Kluyver

That means it doesn't have permission from the operating system to write in that directory. What operating system do you have, and how are you running Jupyter?

If you start an Anaconda command prompt and run `jupyter notebook` from there, does it work? The click-to-launch thing in Anaconda is outside our control.

:-/ Any errors in the browser's Javascript console when this is happening? Have you tried with another browser?

The first error ('Failed to load resource...') might be related, but there's nothing obvious there. Do you have any extensions installed in Chrome?

OK, sounds like that error is not related, then. I recall there was some issue with Lastpass on Chrome before, but that may not be at fault this time.

What browser are you using, and do you see the same if you try it in a different browser?

Does turning off the antivirus make any difference? We've had problems with security software in the past. Also, try it in Firefox and see if the same problem occurs.

Gah, that's annoying. Which platform(s) are people seeing that on? I had assumed `webbrowser` would always launch a browser, but it appears that it can delegate `file://` URLs to the...

We can't launch the browser to an HTTP URL which then redirects to a file, because [redirecting to file:// URLs is not allowed](https://security.stackexchange.com/a/18686).

OK, I'm assuming that the webbrowser module is calling `xdg-open`, while is a wrapper around the desktop's open command (e.g. `gio open ...` on GNOME), and that calling that with...