title: Elasticsearch : Unknown key for a VALUE_STRING in [scroll]
body: <p>Elasticsearch scroll api gives me this error</p>
  
  <pre><code>{
     "error": {
        "root_cause": [
           {
              "type": "parsing_exception",
              "reason": "Unknown key for a VALUE_STRING in [scroll].",
              "line": 2,
              "col": 15
           }
        ],
        "type": "parsing_exception",
        "reason": "Unknown key for a VALUE_STRING in [scroll].",
        "line": 2,
        "col": 15
     },
     "status": 400
  }
  </code></pre>
  
  <p>my code to get documents using scroll api is</p>
  
  <pre><code>GET index/type/_search?scroll=1m
  {
      "size": 1000, 
     "query": {
        "match_all": {}
     }
  }
  </code></pre>
  
  <p>this gives me nice result with <code>"_scroll_id"</code> </p>
  
  <pre><code>{
     "_scroll_id": "DnF1ZXJ5VGhlbkZldGNoBQAAAAAAAB1dFmJRbm9UR3h4UUFTVHFzV1dJMHpuOVEAAAAAAAAdXxZiUW5vVEd4eFFBU1Rxc1dXSTB6bjlRAAAAAAAAHV4WYlFub1RHeHhRQVNUcXNXV0kwem45UQAAAAAAAB1gFmJRbm9UR3h4UUFTVHFzV1dJMHpuOVEAAAAAAAAdYhZiUW5vVEd4eFFBU1Rxc1dXSTB6bjlR",
     "took": 37,
     "timed_out": false,
     "_shards": {
        "total": 5,
        "successful": 5,
        "failed": 0
     },
  </code></pre>
  
  <p>now according to the documentation I should do like this</p>
  
  <pre><code>GET /_search
  {
      "scroll": "1m",
      "scroll_id": "DnF1ZXJ5VGhlbkZldGNoBQAAAAAAAB1dFmJRbm9UR3h4UUFTVHFzV1dJMHpuOVEAAAAAAAAdXxZiUW5vVEd4eFFBU1Rxc1dXSTB6bjlRAAAAAAAAHV4WYlFub1RHeHhRQVNUcXNXV0kwem45UQAAAAAAAB1gFmJRbm9UR3h4UUFTVHFzV1dJMHpuOVEAAAAAAAAdYhZiUW5vVEd4eFFBU1Rxc1dXSTB6bjlR"
  }
  </code></pre>
  
  <p>and this is giving me above error. Am I using scroll api in a wrong way ?
  ES version is 5.5.1 and kibana version is 5.5.1. I am using kibana to access ES server.</p>