Dev Tools appears not to be specifying content-type header

[sophiec20]

Kibana version:
Version: 6.0.0-beta1-SNAPSHOT

Elasticsearch version:
Version: 6.0.0-beta1-SNAPSHOT, Build: 4558fc1/2017-08-07T13:03:07.945Z, JVM: 1.8.0_141

Server OS version:
Linux xxxxx 4.4.35-33.55.amzn1.x86_64 #1 SMP Tue Dec 6 20:30:04 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Browser version: n/a

Browser OS version: n/a

Original install method (e.g. download page, yum, from source, etc.):

downloaded zips

Description of the problem including expected versus actual behavior:

Using Dev Tools, the command below has a syntax error, in that it is missing a comma between the source and dest block.

POST _reindex
{ 
  "source": {
    "index": "filebeat-2017.02.01-old"
  }
  "dest": {
    "index": "filebeat-2017.02.01-new"
  }
}

In elasticsearch and kibana 5.4, this returns a useful json_parse_exception error message

{
  "error": {
    "root_cause": [
      {
        "type": "json_parse_exception",
        "reason": "Unexpected character ('\"' (code 34)): was expecting comma to separate Object entries\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput@1d8b1785; line: 5, column: 4]"
      }
    ],
    "type": "json_parse_exception",
    "reason": "Unexpected character ('\"' (code 34)): was expecting comma to separate Object entries\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput@1d8b1785; line: 5, column: 4]"
  },
  "status": 500
}

In elasticsearch and kibana 6.0.0-beta1, this returns a less useful message

{
  "error": "Content-Type header [text/plain] is not supported",
  "status": 406
}

This message occurs if the Content-Type Header has not been specified for the POST. If specified, then the message from elasticsearch is a json_parse_exception

Steps to reproduce: See description

Errors in browser console (if relevant): n/a

Provide logs and/or server output (if relevant): n/a

[epixa]

@jbudz We just can't win with this console content-type stuff

[jbudz]

No doubt. #12294 should fix this, and we'll have to keep an eye on elastic/elasticsearch#25718. I'm almost thinking we should always set application/json instead of checking for ndjson and be done with it.

[epixa]

I'm almost thinking we should always set application/json instead of checking for ndjson and be done with it.

I am 100% OK with that if it works

[jbudz]

Fixed by #12294