Sorry, brain fart – you have to upgrade between non-LTS releases sequentially, as far as I know there's no supported way to upgrade to 19.04 from anything but 18.10. (in general, to get to release n, you must either be on release n-1, or n must be an LTS and you must be on the previous LTS.)

Yeah but that's what it's trying to do too, and that's exactly what's failing: https://news.ycombinator.com/item?id=19693284

Sorry, totally missed that. Looks like some other people have had similar issues with upgrading to previous versions: https://github.com/Microsoft/WSL/issues/3489 (though the issue is for (I think) 16.04->18.04, someone mentions that it also affects 18.04->18.10)

it's strange that that's all the output you get, though. Apparently it puts logs in /var/log/dist-upgrade/, is there more there?

AHH, thank you! /var/log/dist-upgrade/main.log explains why! It's indeed another instance of a bug I already saw when upgrading another system [1] and couldn't figure out -- there's a missing dependency in some Ubuntu package:

  sudo apt-get install python-distro-info python3-distro-info

EDIT: Do yourself a favor and don't upgrade to 19.04 on WSL. VSCode and google-chrome-stable can't start on it. I had to roll back.

[1] https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upg...