I was working fine earlier today in kubuntu zesty 17.04. I tried to do a restart and then couldn't get past the login screen. It accepted the password but just brought the login screen up again.
I tried them to go into recovery mode and see if any errors appeared. The shell loaded but the filesystem was read only. First it appeared there was an error with mounting the encrypted swap partition. so I disabled mounting that temporarily but it didn't fix the issue. I loaded up a live CD and ran
fsck too. No joy.
There is another error in the recovery shell,
/usr/bin/env: 'node': no such file or directory
Then, on the next line:
couldn't find whiptail, starting root shell instead of recovery menu
When I try
sudo apt-get install whiptail it says it's already installed.