Manuel,
The line below indicates that you have a template override for the SCLogin module:
/home/bcnin/www/templates/rt_momentum/html/mod_sclogin/login.php
The SCLogin module has had large changes in the v3.1 release and you'll need to either remove or update your template override file with the changes.
I hope that helps explain, but if you have any questions, just let me know.
Thanks,
Alex