Can't login to Ubuntu 14.04 after upgrade

What worked for the original poster was: recursively correcting the permissions of their home directory.

sudo chmod -R ug+rwx /home/[username]

To be more specific, the problem is with the .Xauthority in your home folder. You simply need to change its permissions to yourself or, as it was in my case, it was owned by root, so I needed to change the owner to my user. This way you don't need to change the permissions for every file in your home folder.

I am having the same problem. Fixed by chown the whole home directory.

chown -R [user-name]:[user-name] /home/[user-name]

details in this post Unable to mount home-directory for user after fresh install 14.04

I tried this and it worked for me:

sudo apt-get install --reinstall ubuntu-session

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