While migrating to Ubuntu Xenial 16.04 (development distribution), the distribution upgrade was interrupted. Due to inconsistent network while downliading the packages some were corrupted. Hence it resulted in crash of Xenial. The upgrade was successful but the display manager didn't work perfectly.
Main problem is that screen was redirected to the login screen after entering the password. Maybe that specific package was corrupted and it needs to br reconfigured. So do few things from virtual terminal, Ctrl+Alt+F3
First to confirm that your device is upgraded check the distribution specific information. Click Here.
Now you need to type:
sudo dpkg --configure -a
With parameter --configure -a, dpkg configures a package which has been unpacked but not yet configured. If -a or --pending is given instead of package, all unpacked but unconfigured packages are configured. Now all the downloaded packages will be configured and the corrupted / damaged packages while downloading will create error.
To configure these errors and download them again you will be displayed a information in console which says:
Make sure you have an internet connection, because you will need to install libgdk-pixbuf2.0-dev in order to run above command. To install this package again type:gdk-pixbuf-query-loaders > /usrlib/i386-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache
sudo apt-get install libgdk-pixbuf2.0-dev
Now installing this package will automatically download the missing downloads and configure the packages and your upgrade is finally successful after a restart.