There is a work around but it would save space and trouble if this was fixed. [illegal_argument_exception] Fielddata is disabled on text fields by default. Set fielddata=true on [Heading.phrase] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead., called from sub Search::Elasticsearch::Role::Client::Direct::__ANON__ at /usr/local/share/perl/5.20.2/Catmandu/Store/ElasticSearch/Bag.pm line 168.
I've encountered the same issue with Elasticsearch 5.6. Testing 2 client databases, one worked fine, the other threw "fielddata is disabled" errors and failed to search (no results).
I believe this is generally related to the mappings and should be okay for now. Any sort field or facet I think need to be 'keyword' type rather than enabling fielddata