This change only affects development environments using Docker.
We have changed the default set up for ElasticSearch in environments using Docker. In particular, ElasticSearch 7 is now no longer supported and the container is no longer built / run. And the ElasticSearch 2 container is now running on port 9200 (previously 6200).
It is recommended that anyone who was on ES7 switch back to ES2. If you were using ES7 (check settings.ELASTICSEARCH_MAJOR_VERSION) then you should change ELASTICSEARCH_MAJOR_VERSION to 2 and rebuild your elasticsearch databases (./manage.py ptop_preindex) against ES2.
If you were already using ES2, then you may need to change ELASTICSEARCH_PORT to 9200 (from 6200) if you were using Docker.
More details can be found in this pull request: Only use ES version 2 in docker setup by czue · Pull Request #29640 · dimagi/commcare-hq · GitHub