Access denied for custom configuration form translation I get access denied for just the translation page of a config form. I can access the configuration form and update it. No problem there. 
The form lists in config-translation page as well, but when I click on Translate it gives access denied. I'm logged in as Admin. Below is the code as suggested here in my custom module (samplewil.module). 

samplewil.links.menu.yml

samplewil.set_admin:
  title: 'sample settings'
  parent: system.admin_config_system
  description: 'Configure sample settings'
  weight: -10
  route_name: samplewil.set_admin


samplewil.routing.yml

samplewil.set_admin:
  path: '/admin/config/sample-settings'
  defaults:
    _form: '\Drupal\samplewil\Form\SampleForm'
    _title: 'Sample'
  requirements:
    _permission: 'administer site configuration'


samplewil.settings.yml

message: 'Hello'
 langcode: 'ar'


samplewil.config_translation.yml

samplewil.set_admin:
  title: 'Example Translatable config'
  base_route_name: samplewil.set_admin
  names:
    - samplewil.config


samplewil.schema.yml

samplewil.config:
  type: config_object
  label: 'Example config'
  mapping:
    message:
      type: text
      label: 'Message'


My default language is Arabic and I've given 'ar' in settings.yml. 
Any idea why I'm not able to translate?
Got it finally working.
The 'name' array in config_translation was not matching with the actual file. 

samplewil.settings.yml file should be renamed to samplewil.config.yml :)