Breaking changes in 5.4edit

Delete By Query API changesedit

Requests without an explicit query are deprecated and will be invalid in Elasticsearch 6.0.0.

Default settings are no longer supportededit

Previous versions of Elasticsearch allowed a user to set a default setting for any setting. The default setting was only applied if the actual setting was not already set. This feature was trappy, and the complexity that it introduced was prone to bugs. Due to this, we have elected to make a breaking change in a minor release to remove this feature with the exception of default.path.conf, default.path.data, and default.path.logs which remain to support packaging. A future version of Elasticsearch will remove support for these as well, so users should stop relying on this functionality.