Comment 5 for bug 1969822

Thanks for attaching the installer files. Unfortunately the subiquity-server-debug.log is actually a symlink to the real log file, so all we got was an empty symlink.

That said, I can reproduce part of what's going on with the probe-data.
Where I'm confused is the initial state - I think maybe the way things started is that the disks themselves were formatted, without a partition table? Is that correct?

While I'm not yet certain what happened in your case, I've taken a screen recording to show what I would have done at the formatting screen.
https://asciinema.org/a/489119

> I've been able to work around this by selecting Mount -> Other and ignoring the warning about this being dangerous. Both mounting at / and /var/lib produced these warnings. Mounting at /srv did not.

So the concern there is that Subiquity knows we need to write files as part of the install to those partitions, but doesn't know if that is OK to do so. Maybe you're mounting an existing ext4 formatted disk at / and it has stuff - is that going to be ok? In your case it should be fine because you just formatted them, but it doesn't really know that.

The workaround in your case when at the "Editing partition n of /dev/sdX" is to, instead of using "Leave formatted as ext4", to choose the plain "ext4" option which will cause it to be formatted, which should then allow you to mount at "/" without having to choose Other and get a scary-sounding warning.

If you remember, I'm very interested in the initial state of those disks, as I think that's the key to what happened here.