After the today updates, I'm not able to login in Ubuntu.

In GDM, I put user and password, a moment blank screen and return to GDM login screen
In terminal (Ctrl+Alt+F1), login return (without any message) to login promtp
In ssh, the server closes the connection

I'm able to start in recovery mode, but then

i) If I write
login myuser
, I get an "Aborted" message (without any further info.
ii) If I try passwd myuser, I get the same "Aborted" message
iii) I I try adduser, I create a new user correcty, but when I try to login, the same "Aborted"

I cannot see any message in log (syslog, faillog, messages, dmesg).

Any suggestion, help will be welcome. Thanks in advance.