Migrating to 8.6edit

This section discusses the changes that you need to be aware of when migrating your application to Elasticsearch 8.6.

See also What’s new in 8.10 and Release notes.

Breaking changesedit

There are no breaking changes in Elasticsearch 8.6.


The following functionality has been deprecated in Elasticsearch 8.6 and will be removed in a future version. While this won’t have an immediate impact on your applications, we strongly encourage you to take the described steps to update your code after upgrading to 8.6.

To find out if you are using any deprecated functionality, enable deprecation logging.

CRUD deprecationsedit

Deprecate remove_binary default of false for ingest attachment processor

The default "remove_binary" option for the attachment processor will be changed from false to true in a later Elasticsearch release. This means that the binary file sent to Elasticsearch will not be retained.

Users should update the "remove_binary" option to be explicitly true or false, instead of relying on the default value, so that no default value changes will affect Elasticsearch.

Cluster and node setting deprecationsedit

Ensure balance threshold is at least 1

Values for cluster.routing.allocation.balance.threshold smaller than 1 are now ignored. Support for values less than 1 for this setting is deprecated and will be forbidden in a future version.

Set cluster.routing.allocation.balance.threshold to be at least 1.

Mapping deprecationsedit

Deprecate silently ignoring type, fields, copy_to and boost in metadata field definition

Unsupported parameters like type, fields, copy_to and boost are silently ignored when provided as part of the configuration of a metadata field in the index mappings. They will cause a deprecation warning when used in the mappings for indices that are created from 8.6 onwards.

To resolve the deprecation warning, remove the mention of type, fields, copy_to or boost from any metadata field definition as part of index mappings. They take no effect so removing them won’t have any impact besides resolving the deprecation warning.

REST API deprecationsedit

state field is deprecated in /_cluster/reroute response

state field is deprecated in /_cluster/reroute response. Cluster state does not provide meaningful information about the result of reroute/commands execution. There are no guarantees that this exact state would be applied.

Reroute API users should not rely on state field and instead use explain to request result of commands execution.