There must be a very good reason why we complicated our lives with all these technologies ... arguably that is freedom for something. Freedom might be a right but it is never free; so let me demonstrate how I earned it.
Monday, May 15, 2017
Can't login after upgrading to Ubuntu 16.04
After entering password and pressing Enter, the screen just briefly flashed dark then back to the login screen. Same went for Guest Session. Looks like the desktop session is unable to start (or crashes when starting). The system was upgraded from 14.04 and runs inside Virtualbox.
Following advice by Nuno here, I uninstalled nvidia driver and things are back to normal. I had to drop into root shell at boot to do it though.