设置嵌套文档提示index已存在

https://www.elastic.co/guide/c ... .html
按照官网上的教程设置一个字段为嵌套文档，一直报错已存在

{
  "error": {
    "root_cause": [{
      "type": "resource_already_exists_exception",
      "reason": "index [my_index/t7sXaN9MT9aaHb3AmE1txA] already exists",
      "index_uuid": "t7sXaN9MT9aaHb3AmE1txA",
      "index": "my_index"
    }],
    "type": "resource_already_exists_exception",
    "reason": "index [my_index/t7sXaN9MT9aaHb3AmE1txA] already exists",
    "index_uuid": "t7sXaN9MT9aaHb3AmE1txA",
    "index": "my_index"
  },
  "status": 400
}
难道官网上的例子也是错的？