Elasticsearch illegal argument exception

[clash_of_clanss]

Hi,

I am new to elasticsearch concept. I am using ELK (Elasticsearch,Logstash,kibana).

Logstash Config

input {
file {
path => "test.log"
start_position => "beginning"
sincedb_path => "/dev/null"
}
}
filter {
grok {
match => { "message" =>
"(?[\d\s\w\s\d\s\d:\d:\d]+),\d\d\d\s(?[[\w]]+)\s(?[\w-\w-\w-\w-\w]+)\s"}
}
}

 output {
    elasticsearch {
        hosts =>
        ["localhost:9200"]
        index => "test_log"
        }
        stdout
        {
            codec=>rubydebug
         }
}

And the problem is, when I am trying to run this command,
localhost:9200/test_log/_search?pretty' -d '
{
"query": { "match_all": {} }
}'

It throws this error,
{
"error" : {
"root_cause" : [
{
"type" : "illegal_argument_exception",
"reason" : "maxConcurrentShardRequests must be >= 1"
}
],
"type" : "illegal_argument_exception",
"reason" : "maxConcurrentShardRequests must be >= 1"
},
"status" : 400
}

I don't know how to solve this error, anyone knows please share with me.
Thanks.