Can not log on

[x47aw]

Hello, I can no longer log in. I use Sparky Linux with the desktop Openbox.
Last week I pressed the System Upgrade button in the menu.
- Password entered
- then the system reported your system
   is up to date
So nothing has been updated.
I've rebooted.
Was suddenly asked to enter my username and password.
what i did too.
But he does not accept it.
The login screen wakes you up briefly and then comes back.
The username and password are correct.
If I enter a different password, it will be displayed as incorrect.
I've had this bug several times with Sparky Linux. Also on two other computers with different hardware.
So it's not the first time. Then I simply reinstalled the complete system for reasons of time.
Can someone help me how to get the system working again?
Thanks!

[dougm]

Are you using an encrypted home directory (with ecryptfs)?  I've seen this problem with encrypted home dir, when I've changed my password with the passwd command -- not the correct way to do it, should use the Users and Groups GUI.

Other than that, can you login directly as root or another user?  Then examine /home/yourname.  Or check the logs in /var/log

If not, then interrupt the boot sequence by holding down the Shift key, then choose Advanced Options and Recovery Mode from the grub menu.  You can then open a shell as root, and go into /home, see what's there.

[x47aw]

I found the solution, even though it was a long time ago.
I have encountered similar errors several times, be it after an update or if the hard drive is full (in which case you should remove some data from the hard drive).
If the system requires the correct password but cannot be unlocked, you should boot in Advance mode and in
  Terminal the command:

  apt-get clean

input. The system should then function normally again.