Hi Elastic Team,
We are trying to upgrade our Elasticsearch from 5.6 to 6.8.1. We first migrated our ES cluster from 5.6 to 6.8.1 and when we are trying to create new index from curl command we alway get error saying
Failed to parse value  as only [true] or [false] are allowed."}] Error when upgrade from 5.6 to 6.8
Even with a very simple index without any mapping.
curl -X PUT "localhost:9200/test/?pretty=true" -H 'Content-Type: application/json'
We try both with ?pretty=true and without ?pretty=true both get same error.
Do we miss anything from settings or should we add any parameters to the curl command?