I'm actually trying to upgrade from 18.04 to 20.04 using the graphical front end, and at the point 'Installing Upgrades' - 'preparing configuration of libpam0g (amd64)' the process got stuck with these last lines on the command line for some days:
[...]
Preparing to unpack .../12-libapparmor1_2.13.3-7ubuntu5.1_amd64.deb ...
Unpacking libapparmor1:amd64 (2.13.3-7ubuntu5.1) over (2.12-4ubuntu5.1) ...
Preparing to unpack .../13-libselinux1_3.0-1build2_amd64.deb ...
Unpacking libselinux1:amd64 (3.0-1build2) over (2.7-2build2) ...
Setting up libselinux1:amd64 (3.0-1build2) ...
(Reading database ... 251984 files and directories currently installed.)
Preparing to unpack .../libpam0g_1.3.1-5ubuntu4.1_amd64.deb ...
Unpacking libpam0g:amd64 (1.3.1-5ubuntu4.1) over (1.1.8-3.6ubuntu2.18.04.2) ...
Setting up libpam0g:amd64 (1.3.1-5ubuntu4.1) ...
Fontconfig warning: "/etc/fonts/conf.avail/53-monospace-lcd-filter.conf", line 10: Having multiple values in <test> isn't supported and may not work as expected
Checking for services that may need to be restarted...Checking init scripts...
It seems that I could stop the upgrade with Ctrl-C but this may cause an unstable system and seems not the best idea to me...
EDIT/ADD: just tried Ctrl-C but it seems not to stop the process.
The only thing I found was this: https://bugs.launchpad.net/ubuntu/+source/debconf/+bug/1899027 but it seemed not very helpful in my context.
Here is a screen photo of what happens.
What can I do?