Create new field from query

Elastic Stack Elasticsearch
7

when only addressing the filebeat-test-7.8.0-2021.02.01-000100 index i get following error:

{
  "error" : {
    "root_cause" : [
      {
        "type" : "resource_already_exists_exception",
        "reason" : "index [filebeat-test-7.8.0-2021.02.01-000100/Cz1ks68kQ_-bMOhb03PjcA] already exists",
        "index_uuid" : "Cz1ks68kQ_-bMOhb03PjcA",
        "index" : "filebeat-test-7.8.0-2021.02.01-000100"
      }
    ],
    "type" : "resource_already_exists_exception",
    "reason" : "index [filebeat-test-7.8.0-2021.02.01-000100/Cz1ks68kQ_-bMOhb03PjcA] already exists",
    "index_uuid" : "Cz1ks68kQ_-bMOhb03PjcA",
    "index" : "filebeat-test-7.8.0-2021.02.01-000100"
  },
  "status" : 400
}