Looking at your log i see:
Setting up ubuntu-session (3.24.1-0ubuntu8) ...
The script to handle the migration was added in ubuntu-session 3.24.1-0ubuntu11, which was published on 2017-07-06 (later than your upgrade log). Perhaps it had been held in artful-proposed for a couple days.
Looking at your log i see:
Setting up ubuntu-session (3.24.1-0ubuntu8) ...
The script to handle the migration was added in ubuntu-session 3.24.1-0ubuntu11, which was published on 2017-07-06 (later than your upgrade log). Perhaps it had been held in artful-proposed for a couple days.