Content-Type header [application/x-www-form-urlencoded] is not supported on Elasticsearch

Question

To fix this, add curl option -H 'Content-Type: application/json'

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This error is due to strict content-type checking introduced in ElasticSearch 6.0, as explained in this post

Starting from Elasticsearch 6.0, all REST requests that include a body must also provide the correct content-type for that body.

The solution is to add Content-Type: application/json header

curl -XPUT 'localhost:9200/_template/template_1' \
  -H 'Content-Type: application/json' \
  -d '**your query**'

"{ \"name\": { \"first\": {} }, \"address\": [ { \"address1\":\"lane\" } ] } "

In Windows, when you give JSON as a parameter, use double quotes only. Use escape character.