Comment 1 for bug 990426

I had a similar issue, except that I got the disk-space warning when trying to upgrade, so I freed some space, retried and ran into the problems you described.

I think in my case it may be related to some btrfs-issues. I've 15g on / with ~6g in use. During the upgrade it completely fills up. This is probably due to the snapshot apt created of the fs. So in the calculation it does not seem to take into account that the installed_size will be required roughly twice (+ deb-package cache). (Also: it took me ages to find out that the snapshot is eating all the space on the FS…)