# Protect id and type from mass assignment. (default: true)
    # protect_sensitive_fields: true

Problem:
   Invalid configuration option: protect_sensitive_fields.
Summary:
   A invalid configuration option was provided in your mongoid.yml, or a typo is potentially present. The valid configuration options are: :include_root_in_json, :include_type_for_serialization, :preload_models, :raise_not_found_error, :scope_overwrite_exception, :duplicate_fields_exception, :use_activesupport_time_zone, :use_utc.
Resolution:
  Remove the invalid option or fix the typo. If you were expecting the option to be there, please consult the following page with repect to Mongoid's configuration:
 http://mongoid.org/en/mongoid/docs/installation.html (Mongoid::Errors::InvalidConfigOption)