Grails 8 raises the standard build and runtime baseline to Java 21 and uses Gradle 9.6.0. The standard Grails BOM remains on Groovy 5.0.7 and Spock 2.4-groovy-5.0, while Micronaut-enabled Grails applications use Micronaut-specific BOM variants that align with Micronaut 5 and require JDK 25 or later.

Grails 8 is built on Spring Boot 4.1.0 and Spring Framework 7.0.8. This brings the Spring Boot 4 modular artifact layout, Spring Framework 7 API removals, Jackson 3, Tomcat 11 and Jakarta Servlet 6.1, plus Spring Boot 4.1 dependency management for Spring Security 7.1, Spring Data 2026.0 and Micrometer 1.17.

The Grails 8 upgrade guide calls out the major application-impacting changes and links to the Spring Boot 4.0 migration guide, Spring Boot 4.1 release notes and Spring Framework 7.0 release notes.

Grails Forge can now generate applications configured for Grails Data with Hibernate 7. The create-* commands also accept a new -d, --data option (the previous -g and --gorm flags remain supported as legacy aliases) with the values hibernate5, hibernate7, and mongodb; the legacy value hibernate is still accepted and selects Hibernate 5:

Applications generated for Hibernate 7 consume grails-hibernate7-bom — or grails-hibernate7-micronaut-bom when combined with the grails-micronaut feature — consistently across the application dependencies, the buildscript classpath, and buildSrc. This avoids the dependency resolution conflicts that occur when an application generated for Hibernate 5 is manually switched to grails-data-hibernate7 while the default grails-bom remains on the build classpath. The database-migration feature also selects the matching grails-data-hibernate7-dbmigration plugin automatically.

Grails 8 unifies and retimes the plugin lifecycle so that the beans a plugin contributes are registered before Spring Boot processes its auto-configurations. A plugin bean now takes precedence over a Spring Boot default guarded by @ConditionalOnMissingBean — Boot backs off in favour of the plugin’s bean, with no need to override or remove it afterwards.

Plugins register beans through the new beanRegistrar() hook, which returns a Spring Framework BeanRegistrar. Because BeanRegistrar is a functional interface, a closure coerced with as BeanRegistrar is all that is required:

beanRegistrar() replaces the doWithSpring bean builder DSL, which is deprecated in Grails 8. The DSL continues to work for now, but you are strongly urged to migrate. See the upgrade guide for details.

Grails 8 continues the move toward method-based TagLib handlers while preserving compatibility with existing closure-based tags. Method-defined tags now bind named attributes more predictably, exclude inherited framework and Object methods from tag dispatch, and preserve real namespace property getters.

The Grails Gradle extension now defaults preserveParameterNames to true, so application Groovy compilation preserves method parameter names for features such as typed method TagLib arguments.

Tag library unit tests also clean up and rebuild TagLib metadata automatically between features. Tests that use TagLibUnitTest no longer need to manage purgeTagLibMetaClass, and specs that mock additional tag libraries continue to work across feature methods.

Links, form actions, pagination links, sortable column links, redirects, chains, and includes now resolve the target controller namespace automatically when namespace is omitted. In the normal case, where only one controller has the target name, controller and action are enough to generate the correct namespaced or non-namespaced URL. If multiple controllers share the same name, specify namespace to choose one explicitly. Use namespace="" in GSP markup, or namespace: null in Groovy code, to target a non-namespaced controller.

Controllers annotated with @GrailsCompileStatic can now invoke tag library methods without compile-time errors.

Both calling patterns are supported out of the box:

@GrailsCompileStatic recognises controllers and tag libraries by convention and marks tag dispatch points as permissible dynamic calls, while leaving the rest of the class fully type-checked.

Static compilation can now be enabled for every controller, service and tag library in an application from the nested compileStatic block of the grails build configuration, without annotating each class:

All three options are disabled by default and independent, or compileStatic { all = true } can be used as a shortcut to enable all of them. Any class that declares its own @CompileDynamic (or @GrailsCompileStatic/@CompileStatic/@GrailsTypeChecked/@TypeChecked) annotation keeps that setting, so the opt-in never overrides an explicit per-class choice. Tag libraries that still declare tags as closure fields (the deprecated form) are skipped automatically by the tagLibs opt-in — left dynamically compiled with a build warning — so define tags as methods to opt them in. See the GrailsCompileStatic section for details.

Integration tests that implement HttpClientSupport can now use httpPostForm(…​) to send application/x-www-form-urlencoded request bodies. The helper URL-encodes form fields using UTF-8, and repeated values in a Collection or array are encoded as repeated keys in insertion order.

The new grails-testing-support-latency module injects artificial latency into the application under test, so that requests randomly take longer. Slower responses widen the window in which timing bugs occur, turning intermittently flaky functional tests — assertions that race a navigation, missing waits, ordering assumptions — into deterministic failures. The module is inert until grails.testing.latency.enabled is set to true, and the delay range, the fraction of requests affected, and the url patterns are all configurable. See the Functional Testing section for details.

GORM for MongoDB can now declare a TTL index directly in the mapping DSL. Adding expireAfterSeconds to the indexAttributes of a single date-valued property creates a TTL index, and MongoDB automatically removes each document once it reaches the configured age:

A single property can likewise declare a $text index — or another special type such as 2dsphere — through indexAttributes: [type: 'text'].

When the options of an already-created index change between restarts, GORM now reconciles the difference instead of only logging a conflict. A changed TTL is applied in place with MongoDB’s collMod command — no drop, no rebuild — while any other option change is applied by declaring indexAttributes: [recreateOnConflict: true].

A new optional module, grails-data-mongodb-spring-data, lets an application use GORM for MongoDB and Spring Data MongoDB — its MongoTemplate and repositories — side by side over the same MongoClient, database and codecs, and, within a single @Transactional method, the same MongoDB transaction. When the module and spring-data-mongodb are on the classpath of a Spring Boot application that already has a GORM MongoDatastore, it auto-configures a MongoDatabaseFactory, a MongoTemplate and a primary transactionManager over GORM’s existing connection — GORM keeps ownership of the client:

The unified transaction shares GORM’s server-side ClientSession, so it requires GORM multi-document transactions to be enabled (grails.mongodb.transactional = true). Spring Data repositories are enabled the usual way with @EnableMongoRepositories, on a package separate from the GORM @Entity classes; only the connection, codecs and session are shared, and the two object-mapping models stay separate. See the Spring Data MongoDB Interoperability section of the GORM for MongoDB guide for details.