There is no system check with the "%s" tag.

Raise code

                invalid_tag = next(
                    tag for tag in tags if not checks.tag_exists(tag, include_deployment_checks)
                )
            except StopIteration:
                # no invalid tags
                pass
            else:
                raise CommandError('There is no system check with the "%s" tag.' % invalid_tag)

        self.check(
            app_configs=app_configs,
            tags=tags,
            display_num_errors=True,
            include_deployment_checks=include_deployment_checks,
            fail_level=getattr(checks, options['fail_level']),