Incomplete Jackson 2 classpath breaks Grails 8 startup with NoClassDefFoundError in DefaultHttpMessageConverters

Inizia riproducendo il problema con la dipendenza grails-elasticsearch, quindi analizza dependencyInsight e il contenuto di BOOT-INF/lib prodotto da bootJar. Leggi l’elemento dello stack DefaultHttpMessageConverters.detectMessageConverters e confronta gli artefatti Jackson 2 e Jackson 3. Il lavoro è completato quando l’applicazione si avvia senza NoClassDefFoundError, mantenendo il comportamento previsto delle dipendenze Jackson.

Summary

A Grails 8 web application fails to start with NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException as soon as any dependency puts Jackson 2 jackson-core / jackson-annotations on the runtime classpath without Jackson 2 jackson-databind.

Grails 8 ships Jackson 3 for databind (tools.jackson), but the managed platform still supplies Jackson 2 jackson-core, jackson-annotations, and the Jackson 2 dataformat artifacts. When a plugin or library pulls in Jackson 2 core, the resulting classpath has "half of Jackson 2": Spring Framework 7's DefaultHttpMessageConverters.detectMessageConverters() concludes Jackson 2 is available and then hard-references a jackson-databind 2.x class that is not present.

The failure happens while creating OrderedFormContentFilter, so Tomcat never starts and the whole application is dead, regardless of whether the app itself uses Jackson at all.

Found while testing released Grails 7 plugins against 8.0.0-M5.

Grails Version

8.0.0-M5

Java / Groovy Version

Java 21.0.11 (Corretto), Groovy 5.0.8, Spring Boot 4.1.0, Spring Framework 7.0.8

Steps to Reproduce

1. Generate a stock web app with the published 8.0.0-M5 distribution:

grails create-app elasticsearch --profile=web

2. Add a single dependency that transitively brings Jackson 2 core. Any such dependency reproduces it; the one used here is a released Grails 7 plugin:

implementation "org.grails.plugins:grails-elasticsearch:5.1.0"

3. Run gradlew test integrationTest bootJar, or simply boot the app.

Actual Behaviour

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate
  [org.springframework.boot.servlet.filter.OrderedFormContentFilter]:
  Factory method 'formContentFilter' threw exception with message:
  com/fasterxml/jackson/databind/exc/InvalidDefinitionException

Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException
	at org.springframework.http.converter.DefaultHttpMessageConverters$DefaultBuilder.detectMessageConverters(DefaultHttpMessageConverters.java:334)
	at org.springframework.http.converter.DefaultHttpMessageConverters$DefaultClientBuilder.build(DefaultHttpMessageConverters.java:468)
	at org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter.<init>(AllEncompassingFormHttpMessageConverter.java:42)
	at org.springframework.web.filter.FormContentFilter.<init>(FormContentFilter.java:61)
	at org.springframework.boot.servlet.filter.OrderedFormContentFilter.<init>(OrderedFormContentFilter.java:29)
	at org.springframework.boot.webmvc.autoconfigure.WebMvcAutoConfiguration.formContentFilter(WebMvcAutoConfiguration.java:189)

Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.exc.InvalidDefinitionException

Wrapped in WebServerException from TomcatWebServer.initialize, so the context never refreshes.

Root cause evidence

Contents of BOOT-INF/lib in the built bootJar - note Jackson 2 core and annotations are present, Jackson 3 databind is present, and Jackson 2 databind is missing:

BOOT-INF/lib/jackson-core-2.21.5.jar
BOOT-INF/lib/jackson-annotations-2.21.jar
BOOT-INF/lib/jackson-dataformat-cbor-2.21.4.jar
BOOT-INF/lib/jackson-dataformat-smile-2.21.4.jar
BOOT-INF/lib/jackson-dataformat-yaml-2.21.4.jar
BOOT-INF/lib/jackson-databind-3.1.5.jar
BOOT-INF/lib/jackson-core-3.1.5.jar
BOOT-INF/lib/spring-boot-jackson-4.1.0.jar

dependencyInsight shows the Jackson 2 core arriving transitively and being upgraded by the managed platform:

com.fasterxml.jackson.core:jackson-core:2.14.2 -> 2.21.5
\--- org.elasticsearch:elasticsearch-x-content:7.17.29
     \--- org.elasticsearch:elasticsearch:7.17.29
          \--- org.grails.plugins:grails-elasticsearch:5.1.0

com.fasterxml.jackson.core:jackson-core:2.21.4 -> 2.21.5
\--- org.springframework.boot:spring-boot-dependencies:4.1.0

Confirmation of the diagnosis

Adding the missing Jackson 2 databind to the same app:

runtimeOnly "com.fasterxml.jackson.core:jackson-databind:2.21.5"

makes the startup crash disappear entirely. The app then boots, the plugin wires up, and the only remaining failure is the plugin's own ConnectException reaching an Elasticsearch server - an unrelated, expected environmental error:

Caused by: org.elasticsearch.ElasticsearchException at RestHighLevelClient.java:2695
    Caused by: java.util.concurrent.ExecutionException at BaseFuture.java:257
        Caused by: java.net.ConnectException at Net.java:694

So the startup failure is purely the incomplete Jackson 2 classpath, not the plugin's behaviour.

Expected Behaviour

Either the managed platform keeps Jackson 2 internally consistent (if Jackson 2 jackson-core / jackson-annotations are managed and can reach the runtime classpath, Jackson 2 jackson-databind should be managed and present too), or Jackson 2 artifacts should not be able to reach the application runtime classpath at all, so Spring's Jackson 2 detection never triggers.

Right now a user gets a hard, non-obvious startup crash in an unrelated filter, with nothing pointing at the actual cause.

Impact

This is not specific to one plugin. Any Grails 7 plugin or third-party library that brings Jackson 2 core without databind - a very common shape, since many libraries depend on jackson-core or a Jackson 2 dataformat only - will take down a Grails 8 application at startup. The error message names neither Grails nor the offending dependency.

Suggested resolution

Options for discussion:

1. Manage com.fasterxml.jackson.core:jackson-databind (2.x) in the Grails platform alongside the Jackson 2 jackson-core / jackson-annotations / dataformat entries so the Jackson 2 classpath is never half-present.
2. Alternatively, keep Jackson 2 fully off the application runtime classpath and let Jackson 3 be the only Jackson present.
3. At minimum, document this failure mode and the runtimeOnly "com.fasterxml.jackson.core:jackson-databind:<2.x>" workaround in the Grails 8 upgrade guide's Jackson section, since the stack trace gives no hint.

Notes

Part of a compatibility sweep of released Grails 7 plugins against 8.0.0-M5. Related plugin-compatibility issues found in the same sweep: #16122 and #16123. Existing compatibility-shim precedents: #16011 and #16101.