Hello Viktor,

this post is not related to the fact that I still see the error messages, but to the fact it does not make me no longer access the administration panel (incredibly only once yesterday after a refresh).
When I disable all debug options and try to login the login page refresh on http://localhost/admin/index.php but without granting any access to control panel.
On database table "login_attempts" the status is "success" for all my login attempts (I don't know why...).
I tryed to re-download and re-install a full-clean 4.2 version 2 times but with the same results.
If I restore the previous version works perfectly (obviously using 2 different databases).