Edited by morriarthy at 2016-9-8 06:29

It's this problem isn't it?
https://www.youtube.com/watch?v=m5NRl3XQgoM&hd=1
Evem after doing your way it still is stuck in the loop...

Have you tried by deleting ~/.Xauthority in the /home/user directory? I found that solution on one of the debian forums but that didn't worked for me. I found also that maybe reinstalling xorg by entering in the command line sudo apt-get install --reinstall xorg it could solve the problem but I didn't try that one

Edited by savanweylyn at 2016-9-8 20:31

It could be caused either by a changed permission or a full partition. Please post the output of ls -Al and df -h.
If the the owner and group for .Xauthority is not root, then it's the permissions. In this case please do a sudo chown root:root .Xauthority.

If the above is done and you still can't login, then it's a full / or a /home partition (idk how you partitioned your disk at installation). In this case if you don't have a separate /home, then simply run sudo apt-get clean, which will remove the content of /var/cache/apt/archives (you don't need those packages anymore) or if you have a separate /home move or delete some files to free up some disk space, since graphical login needs some, but console login doesn't.

If the owner and group is root for .Xauthority you'll get the same error. So if someone do what you are saying (entering sudo chown root:root .Xauthority) will be still stuck on the loop and also producing a new login loop error, that is to say, more deep into the problem.

So the owner and group needs to be user:user, if is not, you'll have to do sudo chown user:user .Xauthority, obviously changing user with your username.