Today we are pleased to announce the bug fix release of Elasticsearch 2.2.1 based on Lucene 5.4.1. This release is already available on Elastic Cloud, our Elasticsearch-as-a-service platform. Users are advised to upgrade if they find themselves affected by any of the bugs fixed in this version.
More details available in the blog post: https://www.elastic.co/blog/elasticsearch-2-2-1-released