索引模板问题_index_template

_template与_index_template的区别，从旧的es1.7升级到es7.8后，索引模板从__template换成_index_template，会出现下面报错
{"error":{"root_cause":[{"type":"illegal_state_exception","reason":"invalid mapping definition, expected a single map underneath [_doc] but it was: [{properties={device_id={index=true, type=keyword}, updated_at={type=date}, user_id={index=true, type=keyword}, changeable={type=byte}, created_at={type=date}}}]"}],"type":"illegal_state_exception","reason":"invalid mapping definition, expected a single map underneath [_doc] but it was: [{properties={device_id={index=true, type=keyword}, updated_at={type=date}, user_id={index=true, type=keyword}, changeable={type=byte}, created_at={type=date}}}]"},"status":500}