Illegal Argument Exception in Elasticsearch 7.10.1 when Loading data

The problem is highlighted below

curl -sS -H "Content-Type: application/json" -XPOST localhost:9200/test_write_v1/test?pretty -d {
                                                                                  ^
                                                                                  |
                                                                      this should be _doc

Basically, you're creating a default mapping (i.e. for the _doc type) and then you're indexing a document into a specific type called test which doesn't use your default mapping. You should not do that.