Breaking changes in 2.3

This section discusses the changes that you need to be aware of when migrating your application to Elasticsearch 2.3.

A change to the CORS implementation means that CORS support for pre-flight OPTIONS requests is broken in 2.3.0 and 2.3.1. This is fixed in 2.3.2.

Indexing a document with 100 nested fields actually indexes 101 documents as each nested document is indexed as a separate document. To safeguard against ill-defined mappings the number of nested fields that can be defined per index has been limited to 50. This default limit can be changed with the index setting index.mapping.nested_fields.limit. Note that the limit is only checked when new indices are created or mappings are updated. It will thus only affect existing pre-2.3 indices if their mapping is changed.

In previous versions of Elasticsearch, the Groovy scripting capabilities depended on the org.codehaus.groovy:groovy-all artifact. In addition to pulling in the Groovy language, this pulls in a very large set of functionality, none of which is needed for scripting within Elasticsearch. Aside from the inherent difficulties in managing such a large set of dependencies, this also increases the surface area for security issues. This dependency has been reduced to the core Groovy language org.codehaus.groovy:groovy artifact.

The deprecated filters/token_filters/char_filters parameter has been renamed filter/token_filter/char_filter. And filters/token_filters/char_filters has been removed in 5.0.0