Devise NoMethodError 'for' ParameterSaniti

I'm going nuts with an error I'm getting every time I try to sing in/sing up on my web.

Heroku logs:

Started GET "/users/sign_in" for 201.235.89.150 at 2016-07-06 01:35:03 +0000
 Completed 500 Internal Server Error in 3ms (ActiveRecord: 0.0ms)
NoMethodError (undefined method `for' for #<Devise::ParameterSanitizer:0x007f5968e0a920>):
 app/controllers/application_controller.rb:11:in `configure_permitted_parameters'

application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  before_filter :configure_permitted_parameters, if: :devise_controller?

    protected

        def configure_permitted_parameters
            devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(:username, :email, :password, :provider, :uid) }
            devise_parameter_sanitizer.for(:account_update) { |u| u.permit(:username, :email, :password, :current_password) }
        end
end

The thing is it is working fine locally. It´s just on Heroku. And also it was working just fine a couple of days ago.

class ApplicationController < ActionController::Base    
  before_action :configure_permitted_parameters, if: :devise_controller?

  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_up, keys: [:first_name, :last_name, :email])
    devise_parameter_sanitizer.permit(:account_update, keys: [:first_name, :last_name, :phone, :email, bank_attributes: [:bank_name, :bank_account]])
  end
end

"The .for method is deprecated in 4.1 +

The first arg is the action name. :sign_up is for creating new Devise resources (such as users), and :account_update is for editing/updating the resource.

The second arg, :keys contains an array of the parameters you allow.

If you want nested_attributes, there is an example in :account_update, you put a separate array in with the key being _attributes."