Mapping issue: unsupported parameters

[Di_Zou]

Need some help here. I am not sure what is problem with my mapping.

I am using elasticsearch 5.3.1. I got an error from my logstash:

unsupported parameters: [properties : {arn={fields={keyword={ignore_above=256, type=keyword}}, type=text}, userName={fields={keyword={ignore_above=256, type=keyword}}, type=text}}]

the related template:

"userIdentity": {
          "properties": {
            "arn": {
              "fields": {
                "keyword": {
                  "ignore_above": 256,
                  "type": "keyword"
                }
              },
              "type": "text"
            },
            "userName": {
              "fields": {
                "keyword": {
                  "ignore_above": 256,
                  "type": "keyword"
                }
              },
              "type": "text"
            }
          }
        }