[eluser]Maulwurf[/eluser]
1.5 until 1.7.2 for example.
"Note: To display errors this way you must remember to set your fields using the $this->validation->set_fields function described earlier. The errors will be turned into variables that have "_error" after your field name. For example, your "username" error will be available at:
$this->validation->username_error."
from comparing the old and the new docs, I'd say, set_fields has gone and has merged into set_rules, which now takes 3 parameters instead of one.