code: def handle_resource_not_found(resource):
      
      resource.set_erred()
      resource.runtime_state = ''
      message = 'Does not exist at backend.'
      if message not in resource.error_message:
          if not resource.error_message:
              resource.error_message = message
          else:
              resource.error_message += ' (%s)' % message
      resource.save()
      logger.warning('%s %s (PK: %s) does not exist at backend.' % (
          resource.__class__.__name__, resource, resource.pk))
docs: Set resource state to ERRED and append/create "not found" error message.