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Spring Boot 4.0.0 M2 Release Notes

Andy Wilkinson edited this page Aug 4, 2025 · 3 revisions

Spring Boot 4.0.0-M2 Release Notes

Upgrading from Spring Boot 3.5

Elasticsearch Client

In response to changes in Elasticsearch, auto-configuration for the now-deprecated low-level Elasticsearch RestClient has been replaced with auto-configuration for the new Rest5Client. If you were using Spring Boot’s RestClientBuilderCustomizer to customize the client, you must now use Rest5ClientBuilderCustomizer instead.

As part of the changes in Elasticsearch, the client code has been consolidated in the co.elastic.clients:elasticsearch-java module, including built-in sniffer support. The org.elasticsearch.client:elasticsearch-rest-client and org.elasticsearch.client:elasticsearch-rest-client-sniffer modules are no longer required and Spring Boot’s dependency management for them has been removed.

Support for the higher-level ElasticsearchClient and the Spring Data Elasticsearch-provided ReactiveElasticsearchClient remains. It has been updated to use the new low-level client.

New and Noteworthy

Tip
Check the configuration changelog for a complete overview of the changes in configuration.

Dependency Upgrades

Spring Boot 4.0.0-M2 moves to new versions of several Spring projects:

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Numerous third-party dependencies have also been updated, some of the more noteworthy of which are the following:

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Miscellaneous

Apart from the changes listed above, there have also been lots of minor tweaks and improvements including:

  • Public members (aside from constants) have been removed from auto-configuration classes. Auto-configurations never have been public API and now this is enforced through Java mechanisms.

Deprecations in Spring Boot 4.0.0-M2

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