[[breaking_60_rest_changes]]
=== REST changes

==== Unquoted JSON

In previous versions of Elasticsearch, JSON documents were allowed to contain unquoted field names.
This feature was removed in the 5.x series, but a backwards-compatibility layer was added via the
system property `elasticsearch.json.allow_unquoted_field_names`. This backwards-compatibility layer
has been removed in Elasticsearch 6.0.0.

==== Analyze API changes

The deprecated request parameters and plain text in request body has been removed. Define parameters in request body.

==== Indices exists API

The `ignore_unavailable` and `allow_no_indices` options are no longer accepted
as they could cause undesired results when their values differed from their
defaults.