Uninitialized constant for autoload_paths when migrate to Rails 6

Question

I have project on ruby 2.6.2 and rails 5.2.3. I successfully migrate to ruby 3.1.3. And now try migrate to Rails 6.1.7.3.

But when I try to run rails c, I get next exception:

uninitialized constant DateUtils (NameError)

DateUtils is a module in app/utils folder: app/utils/date_utils.rb

module DateUtils
  module_function

In config/application.rb I have next code:

config.autoloader = :classic
config.autoload_paths += Dir[Rails.root.join('app', 'utils')]

What could be the problem?