Err: top-level object must be a mapping

Docker Engine Swarm
,
10

I ran it locally and it gives me this when doing the docker compose config:

service "backend" refers to undefined volume media_volume/: invalid compose project

The service name change with every command.

compose lines:

  backend: &backend
    image: ${CONTAINER_IMAGE:-backend}
    environment:
      MY_ENVIRONMENT: ${ENVIRONMENT:-dev}
    expose:
      - 5000
    volumes:
      - media_volume/:/app/files
 ...   
volumes:
  redis_volume:
  postgres_volume:
  media_volume:
  static_volume:
  flower_volume:

Does this solve it? I do not want to lose my data:

Lastely:
it looks like removing the slash from “media_volume/” helps but does changing this mess up with my existing volume mapping?