Connect_exception null error during reindex

Elastic Stack Elasticsearch
1

Hello,

I'm trying to use the /_reindex from remote api with the query:

POST /_reindex

{
  "source": {
    "index": "existing_index"
  },
  "dest": {
    "index": "new_index"
  }
}

I got:

{
	"error": {
		"root_cause": [{
			"type": "connect_exception",
			"reason": null
		}],
		"type": "connect_exception",
		"reason": null
	},
	"status": 500
}

What should I do on this error?

Thank you!

2

show the master node for detailed log
maybe add setting about index.