Undefined index: array_parents

I'm getting this error on a multiple video embed field:

• Notice: Undefined index: array_parents in field_default_form_errors() (line 342 of /Users/elena/Sites/maple/modules/field/field.form.inc).
• Recoverable fatal error: Argument 2 passed to drupal_array_get_nested_value() must be an array, null given, called in /Users/elena/Sites/maple/modules/field/field.form.inc on line 342 and defined in drupal_array_get_nested_value() (line 6341 of /Users/elena/Sites/maple/includes/common.inc).

Also I cannot find the admin configuration area, where is it?