Trying to put new mapping, getting 404

Elastic Stack Elasticsearch
1

I'm trying to update data mapping for two types so I can use them in visualize but I am getting a 404 in return. I followed every example I can find and I don't understand what I need to do to just make mapping work. Seems like something that should be configurable through Kibana itself. Using v. 2.4.0 for Elasticsearch and Logstash, v. 4.6.1 for Kibana.

Here's my request:

PUT /psslogs/_mapping/message HTTP/1.1
Host: localhost:5601
Content-Type: application/json
kbn-version: 4.6.1
Cache-Control: no-cache

{
	"properties": {
		"ApiData": {
			"properties": {
				"RequestUri": {
					"type":"string",
					"index":"not_analyzed"
				}
			}
		}
	}
}

The format of the field I'm attempting to update is message.ApiData.RequestUri.

2

I think if you specify the type you shouldn't have two layers of properties. At least, the examples here don't. I'm not sure about the 404 though. What is the body of the 404?