Comment 30 for bug 1839237

If it is stuck on 0% but still writing to the disk, then it's either getting errors from the network or when starting a download, or downloading the first chunks fails for some reason. In any case, it would be useful to find out why. Specifically, as you noted restarting snapd helps, which may suggest something network state related.

If you can reproduce it, would you be willing to add the following to /etc/environment and restarting snapd?

SNAPD_DEBUG=1
SNAPD_DEBUG_HTTP=7

Then once the problem occurs, please collect the output of journalctl -u snapd.

Perhaps trying to reboot the system and then trying `snap install <some-large-snap eg. xonotic>` would reproduce it.