When type is declared as string, Elasticsearch 6.0 will show this error.
type
string
"name" => [ "type" => "string", "analyzer" => "ik_max_word" ]
Elasticsearch 已经删除了 string类型,现在使用的是 text
text
"name" => [ "type" => "text", "analyzer" => "ik_max_word" ]