I used do-release-upgrade to switch from 14.04 to 16.04. After the upgrade cycle I rebooted and the boot gets stuck at upgrading the UTMP
This is a similar problem to here, however when I accessed the command line I am unable to use apt-get as well, I get this error:
Relocation error: /usr/lib/x86_64-linux-gnu/libapt-pkg.so.5.0 symbol_znk.... Version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference
So I'm guessing aptitude was lost in the failed upgrade...
Any help would be greatly appreciated
Edit: I can also see some failed steps before it got stuck:
Failed to start detect the available GPUs and deal with system changes...
Failed to start light display manager...
Failed to start network manager wait online...
UPDATE: The user cowedly gave up on recovery and just reinstalled 16.04. Better luck for the next one.