[[breaking_50_rest_api_changes]]
=== REST API changes

==== id values longer than 512 bytes are rejected

When specifying an `_id` value longer than 512 bytes, the request will be
rejected.

==== `/_optimize` endpoint removed

The deprecated `/_optimize` endpoint has been removed. The `/_forcemerge`
endpoint should be used in lieu of optimize.

The `GET` HTTP verb for `/_forcemerge` is no longer supported, please use the
`POST` HTTP verb.

==== Removed `mem` section from `/_cluster/stats` response

The `mem` section contained only one value, the total memory available
throughout all nodes in the cluster. The section was removed as it didn't
prove useful.