I just upgraded our machine from Ubuntu 14.04 to Ubuntu 16.04.1. After the upgrade, the desktop no longer opens. I just got to a black screen.
Also, when I tried to run sudo apt followed by anything, I got the following error:
apt-get: relocation error: /usr/lib/x86_64-linux-gnu/libapt-pkg.so.5.0: symbol _ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE7compareERKS4_, version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference
Any help is great appreciated. Thanks.