Hey Andreas, yeah, I was trying to get a similar error when the shard fails because of a complex query, but it seems that in that case I always get all shards failing - and that results in OpenSearch returning a 400 status code… the test case I have right now is generating that “one shard failed while the other didn’t” state, but for a different underlying reason, so we probably are ok on that side… Although if you’ll have time to create another test case with a query like you have in the description, that would also be nice 🙂.

As for the backporting, we probably can, but I’ll defer the final answer on that to Yoann Rodière.