Change the Elasticsearch Client
As of version 2.3.7, Adobe Commerce supports Elasticsearch 7.9.3 but should work with 7.x. Support for Elasticsearch 6.x has been deprecated. Elasticsearch 2.x and 5.x have reached end-of-life and are no longer supported.
Change the Elasticsearch Client version
If you need to work with Elasticsearch 7.x, run the following command, specifying your desired version:
1 composer require "elasticsearch/elasticsearch:~7.1"
Then configure Elasticsearch within Admin.