I have very similar issues to those reported here. Upgraded to 16.04 from 15.10 (from australia - au.archive.ubuntu.com seemed flakey when I started, but got there after a few days of trying). Couldn't start plasma, could only get to a terminal prompt. Running startx yielded the exact screen grabs that dpeets attached.
>From there I purged nvidia drivers and somehow got to the plasma log in screen. No progress after hitting enter on the log in screen. By some accident I plugged an HDMI cable into my laptop, and then plasma loaded. I've verfified this a number of times. plasma only starts fully when an hdmi cable is connected to an external display! I tried purging snapd (I have no idea what that is) but no difference. I also have the weird double '//' in my $XDG_DATA_DIRS env var: echo $XDG_DATA_DIRS /usr/share//usr/share/xsessions/plasma:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1576500 Title: Plasma fails to load: "all shell packages missing" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/plasma-desktop/+bug/1576500/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
