Micronaut Blog

JSpecify nullability annotations have emerged as the standard way to define nullability constraints in Java APIs using annotations. We have migrated Micronaut’s internal APIs to use JSpecify nullability annotations. If you were using Micronaut nullability annotations, replace usages of io.micronaut.core.annotation.Nullable with org.jspecify.annotations.Nullable, and usages of io.micronaut.core.annotation.NonNull with org.jspecify.annotations.NonNull. Fully Qualified Types When specifying a fully...

Since Micronaut Framework 3.3.0, you can use Micronaut Serialization as an alternative to Micronaut Jackson Databind. Moreover, the framework exposes low-level APIs such as JsonMapper to avoid coupling between serialization implementations. Micronaut Jackson Databind internally used Jackson 2. With the release of Micronaut 5, Micronaut Jackson Databind (micronaut-jackson-databind) uses Jackson 3. See the Jackson 3...

Micronaut Framework 5.0, to be released in Q2 2026, drops support for RxJava 2. Micronaut 5 users have two reactive options: Project Reactor or RxJava 3. Micronaut public APIs are reactive library–agnostic. However, internally, when a reactive library is required, we use Project Reactor. If you want to migrate from RxJava 2 to RxJava 3,...

Micronaut Framework 5.0, to be released in Q2 2026, supports Apache Groovy 5. Apache Groovy 5.0 adds new features such as: Broader JDK Support Substantial Extension Method Expansion Enhanced AST Transforms Revamped REPL (groovysh) Improved Java Interoperability Modern Web Standards Type Checking Enhancements Additional Language Goodies

Micronaut Framework 5.0, to be released in Q2 2026, supports Kotlin 2.3. Kotlin 2.3. main highlights are: Language: More stable and default features, unused return value checker, explicit backing fields, and changes to context-sensitive resolution. Kotlin/JVM: Support for Java 25. Kotlin/Native: Improved interop through Swift export, faster build time for release tasks, C and Objective-C...

Starting with Micronaut Framework 5.0, to be released in Q2 2026, the Java baseline will be Java 25. Use modern Java features By setting a Java 25 baseline, we can improve our internal code and public APIs by continuing to use features such as Virtual Threads, Structured Concurrency, Scoped Values, Pattern Matching for switch, Record...

Today, we are announcing that the Micronaut framework is applying to join the Commonhaus Foundation. This is an exciting new step in the Micronaut project’s journey, and we’re looking forward to the opportunity to continue innovating with our community under the Commonhaus Foundation banner. As is customary at the turn of a new year, we’d...

Micronaut HTTP Server Netty 4.9 introduces a new, experimental “loom carrier mode” for the Netty event loop. This prototype uses internal JDK APIs to run virtual threads directly on the event loop, under control of the framework. Our goal is to provide performance characteristics comparable to reactive code, with the convenience and “safety net” that...

Sonar has published a blog post about their use of Micronaut and AWS Lambda Snapstart. It is possible to generate a Micronaut Application with AWS CDK ready to be deployed to Lambda with the Micronaut CLI Command mn create-aws-lambda or selecting the aws-lambda, aws-cdk features in Micronaut Launch. It is great to see that...

Loic Mathieu, Lead Software Engineer at Kestra, shared with us how they use the Micronaut framework at Kestra. We published “Micronaut Framework at Kestra” success story. But as enjoyable as it is for us to learn the framework usage within a company, it is as interesting to learn why technology is adopted and how they...

Agorapulse published a blog post about their Micronaut journey. Micronaut fully met our expectations. The framework is still very active, and many team members found its new home in Oracle Labs GraalVM Team. This sends a strong message that the development will not be discontinued in the near future. There is also a friendly, vibrant...

We are happy to welcome YourKit as a Tools and Infrastructure partner of the Micronaut Foundation. YourKit supports open source projects with innovative and intelligent tools for monitoring and profiling Java and .NET applications. YourKit is the creator of YourKit Java Profiler, YourKit .NET Profiler, and YourKit YouMonitor.

The Micronaut Foundation is happy to announce that you can follow us on Mastodon at fosstodon.org/@micronaut. With the Micronaut framework being an open-source project, we chose Fosstodon as the Mastodon instance. Fosstodon is a Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software. Mastodon is an...

The Micronaut® framework engineering team confirmed a security vulnerability in the management module, discovered by Joseph Beeton of Contrast Security, Inc. This vulnerability is assigned the identifier CVE-2024-23639. Summary A susceptible environment is where the application runs locally, management endpoints are enabled but unsecured, and the local host accesses an unrelated but problematic website. This...

Micronaut framework is so fortunate to have an engaging community with many supportive contributors. Micronaut Core alone has close to 400 contributors. As a contributor to the Framework, the signature of a Contributor License Agreement is required. With the recent partnership between Micronaut Foundation with Unity Foundation, we are updating our Contributor License Agreement. Please...

The Micronaut team confirmed a security vulnerability found in the Micronaut Security Oauth2 dependency, identified and reported by Tommy Li. This vulnerability is assigned the identifier CVE-2023-36820. Summary When using a vulnerable version of micronaut-security-oauth2, the IdTokenClaimsValidator skips aud claim validation if the same authorization server issues the token. Affected Versions Micronaut Security versions greater...

Moving to Discord The Micronaut Foundation has decided to make a switch and move our chat community to a new platform. Effective immediately, we are moving the community chat from Gitter to Discord. Why are we moving to Discord? Discord provides an improved desktop app experience, better-structured conversations, enhanced notifications, etc. Thus, it gives the...

The Micronaut team has assembled a new set of OpenRewrite recipes to make upgrading from Micronaut Framework 3 to Micronaut Framework 4 quick and straightforward. These recipes automate as much as possible from our previous “Upgrade To Micronaut Framework 4” post. The recipes will be continually updated whenever we discover new upgrade steps. Upgrading a Gradle Application...

The Micronaut team has assembled a new set of OpenRewrite recipes to make upgrading from Micronaut Framework 3 to Micronaut Framework 4 quick and straightforward. These recipes automate as much as possible from our previous “Upgrade To Micronaut Framework 4” post. The recipes will be continually updated whenever we discover new upgrade steps. Upgrading a Maven Application...

This post is a migration guide from Micronaut Framework 3 to Micronaut framework 4.0. You can read about Micronaut core 4 breaking changes. Moreover, To ease upgrading, we provide OpenRewrite integration for Gradle and Maven. Logback Remove true from src/main/resources/logback.xml Gradle Applications Version update Set micronautVersion property in gradle.properties. micronautVersion=4.0.0 Update Gradle to 8 Micronaut...

Town Hall Meetings provide the Groovy, Grails, and Micronaut communities a place to gather once per quarter to review the most up-to-date news and resources available, celebrate accomplishments, ask questions, and participate more fully in our OSS ecosystems.

When you develop a Micronaut application, you write .java, .kt, or .groovy files. Through this article, I refer to those files as source code. The Java compiler compiles source code into a new document suffixed .class, coded into Java bytecode. The compiled bytecode is platform-independent. A device capable of running Java can interpret/translate this file...