Hi @DavidTurner, let me rephrase the question, because I feel as though this going around in circles.
Elasticsearch was upgraded to 6 in the background in development, and afterwards stopped working because the schema contained type fields, which — as explained in the breaking changes — is deprecated. I've since fixed this with the new schema and a re-indexing.
What I need to know is, if I do a scheduled upgrade, from an index that is based on the same index structure and schema as the development version (5.6), would that also become broken (requiring a re-index), or would there be some process to use the new schema?