Elastic Cloud Serverless breaking changes

In earlier versions of Elasticsearch, ES|QL would fail the entire query if it encountered any error. ES|QL now returns partial results instead of failing when encountering errors.

Impact:

Callers should check the is_partial flag returned in the response to determine if the result is partial or complete. If returning partial results is not desired, this option can be overridden per request via an allow_partial_results parameter in the query URL or globally via the cluster setting esql.query.allow_partial_results.

For more information, view #125060.

The exclude_source_vectors setting is now enabled by default for newly created indices. This means that vector fields (for example, dense_vector) are no longer stored in the _source field by default, although they remain fully accessible through search and retrieval operations. Instead of being persisted in _source, vectors are now rehydrated on demand from the underlying index structures when needed. This reduces index size and improves performance for typical vector search workloads where the original vector values do not need to be part of the _source. If your use case requires vector fields to be stored in _source, you can disable this behavior by setting exclude_source_vectors: false at index creation time.

Impact:

Vector fields will no longer be stored in _source by default for new indices. Applications or tools that expect to see vector fields in _source (for raw document inspection) may need to be updated or configured to explicitly retain vectors using exclude_source_vectors: false. Retrieval of vector fields via search or the _source API remains fully supported.

For more information, view #131907.

Roles with explicit read access to advanced settings but all access to SavedObjectManagement can no longer update settings via the internal advanced settings API. This update enforces explicit privileges instead of relying on saved object security checks.

For more information, view #230067.

Previously, the ES|QL grammar allowed users to individually quote constituent strings in index patterns such as "remote_cluster":"index_name". This would allow users to write complex malformed index patterns that often slip through grammar and the subsequent validation. This could result in runtime errors that can be misleading. This change simplifies the grammar to early reject such malformed index patterns at the parsing stage, allowing users to write simpler queries and see more relevant and meaningful errors.

Impact:

Users can write queries with simpler index patterns and see more meaningful and relevant errors. For more information, view #127636.