Comment 6 for bug 1903838

This issue occured again today when upgrading another server from 18.04 to 20.04

here is a snippet and i'll try to guess what may be happening

==========
Stopping some services possibly affected by the upgrade (will be restarted later):
  cron: stopping...done.

Unpacking libc6:amd64 (2.31-0ubuntu9.9) over (2.27-3ubuntu1.5) ...

Progress: [ 16%]
/usr/bin/perl: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory
dpkg: error while cleaning up:
 rm command for cleanup subprocess returned error exit status 127
/usr/bin/perl: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory
dpkg: error processing archive /tmp/apt-dpkg-install-HpZRay/04-libcrypt1_1%3a4.4.10-10ubuntu4_i386.deb (--unpack):
 rm command for cleanup subprocess returned error exit status 127
=======

We had i386 architecture installed on this server due to an old 32bit program, could this be caused by the upgrade of the 32bit version of libcrypt1 ?

We also had a systemd unit running swatch on some log files which runs with perl which was not stopped like cron did , could this also cause perl to fail ?

My last guess would be if that safe-rm is installed somehow doesn't return correctly and should be removed before the upgrade

I hope my observations helps you solve this issue