This should be the Registration UI

You ended up here because you didn't set the following configuration value:

path/to/kratos/config.yml

selfservice:
  flows:
    registration:
      ui_url: http://my-app.com/registration

You can set this configuration value using environment variable SELFSERVICE_FLOWS_REGISTRATION_UI_URL as well!

If you don't know what that means, head over to Self-Service User Registration!