I am on a binge upgrade of servers from Ubuntu 16.04 to 18.04. Some of the upgrades are going fine and some of the servers the upgrade hangs at this point:
Preparing to unpack .../libnih1_1.0.3-6ubuntu2_amd64.deb ... Unpacking libnih1:amd64 (1.0.3-6ubuntu2) over (1.0.3-4.3ubuntu1) ... Processing triggers for libc-bin (2.27-3ubuntu1) ... Setting up libnih1:amd64 (1.0.3-6ubuntu2) ...
This is a known pitfall and the work around is found here.
I am interested in knowing is why is this happening?
PS: These are all systems which are just been upgraded to 16.04 from 14.04 and are almost close to bare Ubuntu.