The analyzer did not find query string execution on top of elasticsearch couchdb river

Question

The analyzer did not find query string execution on top of elasticsearch couchdb river

Pretty sure that I am making some kind of huge mistake, but I don’t know how to sort it.

My couchdb river and my index are defined as follows:

curl -XPUT 'localhost:9200/_river/my_index/_meta' -d '{
"type" : "couchdb",
"couchdb" : {
    "host" : "localhost",
    "port" : 5984,
    "db" : "my_db",
    "filter" : null
},
"index" : {
    "index" : "my_index",
    "type" : "my_index_type",
    "bulk_size" : "100",
    "bulk_timeout" : "10ms",
    "analysis": {
        "analyzer": {
            "tags_analyzer": {
                "type" : "custom",
                "tokenizer": "lowercase",
                "filter": ["lowercase", "asciifolding"]
            }
        }
    }
},
"mappings": {
    "tags": {
        "properties": {
            "tags": {
                "type": "string",
                "analyzer": "tags_analyzer",
                "boost": 10
            }
        }
    }
}}'

The request is executed using the JAVA application:

 QueryStringQueryBuilder queryBuilder = QueryBuilders.queryString(req.getParameter("tags"));
        queryBuilder.defaultField("tags");
        queryBuilder.analyzer("tags_analyzer");
        queryBuilder.analyzeWildcard(true);
        queryBuilder.lowercaseExpandedTerms(true);
        queryBuilder.defaultOperator(QueryStringQueryBuilder.Operator.AND);

        SearchResponse response = client.prepareSearch("idxscopus").setSearchType(SearchType.QUERY_THEN_FETCH).setQuery(queryBuilder)
                .addHighlightedField("tags", 0, 0)
                .setFrom(0).setExplain(true).execute().actionGet();

During the query phase, I encounter a QueryParsingException saying that my user analyzer is missing:

omquery򋱵ery_string򁂪b*default_fieldCtagsdefault_operatorBandanalyzerLtags_analyzerlowercase_expanded_terms#analyze_wildcard#󻆥xplain#highlight򅦩elds򃴡gs򌦲agment_sizenumber_of_fragments;󻻀]]]; nested: QueryParsingException[[idxscopus] [query_string] analyzer [tags_analyzer] not found]; }{[BtMQ0EBJQVmFKyJTJMVhSA][idxscopus][1]: RemoteTransportException[[Aardwolf][inet[/10.1.1.2:9300]][search/phase/query]]; nested: SearchParseException[[idxscopus][1]: from[0],size[-1]: Parse Failure [Failed to parse source [:)