curl localhost:9200
{
  "name" : "84ucGje",
  "cluster_name" : "elasticsearch_dnk306",
  "cluster_uuid" : "yU6wdZpJT_-1OvaFf7l7Ug",
  "version" : {
    "number" : "6.5.0",
    "build_flavor" : "default",
    "build_type" : "tar",
    "build_hash" : "816e6f6",
    "build_date" : "2018-11-09T18:58:36.352602Z",
    "build_snapshot" : false,
    "lucene_version" : "7.5.0",
    "minimum_wire_compatibility_version" : "5.6.0",
    "minimum_index_compatibility_version" : "5.0.0"
  },
  "tagline" : "You Know, for Search"
}

curl -XPOST localhost:9200/test/1 -d '{"title":"Hello world"}'
{"error":"Content-Type header [application/x-www-form-urlencoded] is not supported","status":406}