Downgrading elasticsearch in docker-compose.yml leads to license error - docker

Question

I have the following docker-compose.yml file:
...
elasticsearch:
image: docker.elastic.co/elasticsearch/elasticsearch:5.4.3
container_name: elasticsearch-cust-comp
...
I've previously run it with another elasticsearch version:
...
elasticsearch:
image: docker.elastic.co/elasticsearch/elasticsearch:6.5.4
container_name: elasticsearch-cust-comp
...
Since changing the version to 5.4.3, I'm getting this error in docker logs for the Elasticsearch container:
Unknown license version found, please upgrade all nodes to the latest elasticsearch-license plugin
My guess is that version 6.5.4 of Elasticsearch is still running somewhere and that it creates issues when I'm trying to run 5.4.3. But as far as I know, I've shut down all Elasticsearch containers currently running with docker-compose down, and docker ps shows no processes after this. Still, when I run docker-compose up -d with version 5.4.3, it gives me this error. Running 6.5.4 works fine. What do I need to do to be able to run version 5.4.3?
EDIT:
This is the whole part regarding elasticsearch in the docker-compose.yml. As you can see, xpack is already disabled:
elasticsearch:
image: docker.elastic.co/elasticsearch/elasticsearch:5.4.3
container_name: elasticsearch-cust-comp
ports:
- 9200:9200
- 9300:9300
volumes:
- cust-comp-elastic:/usr/share/elasticsearch/data
- ./cust/externalConfig/elasticsearch/config/hunspell/:/usr/share/elasticsearch/config/hunspell/
# - ./config/elasticsearch/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml
# - ./fwhome/elasticsearch/cust-comp:/usr/share/elasticsearch/config/cust-comp
networks:
- cust-comp
environment:
- cluster.name=i3-elasticsearch
- xpack.security.enabled=false
- xpack.monitoring.enabled=false
- xpack.ml.enabled=false
- xpack.graph.enabled=false
- xpack.watcher.enabled=false
restart: unless-stopped

Answer 1

In doubt, try:
docker system prune
This will clean unused containers/images.