Jackson 2 and Jackson 3

declare your own Jackson 2 mapper, which Camel discovers:

@Bean
com.fasterxml.jackson.databind.ObjectMapper camelObjectMapper() {
    return new com.fasterxml.jackson.databind.ObjectMapper(); // configure as needed
}

or add org.springframework.boot:spring-boot-jackson2 (deprecated in Spring Boot 4) and rename your spring.jackson. properties to spring.jackson2.. Properties under spring.jackson.* only configure Spring Boot’s Jackson 3 mapper.

Check that the application can move:

Find the Jackson 2 code in your application:

grep -rlE 'com\.fasterxml\.jackson\.(core|databind|datatype|dataformat|module)' src/
mvn dependency:tree -Dincludes=com.fasterxml.jackson.core,com.fasterxml.jackson.datatype,org.apache.camel:camel-jackson

Add tests that capture the JSON your routes and REST endpoints produce and accept today: marshal a representative object and compare it with a stored file, and unmarshal stored payloads. Run them before and after the migration. Most Jackson 3 changes do not raise errors; they produce different JSON.

Routes. marshal().json(), json(JsonLibrary.Jackson), marshal("jackson"), REST DSL binding and the application-json transformers keep working unchanged. Only Java code that creates the data format changes its import: org.apache.camel.component.jackson.JacksonDataFormat becomes org.apache.camel.component.jackson3.JacksonDataFormat. The same applies to ListJacksonDataFormat, to the XML, Avro and Protobuf data formats, and to class names referenced in YAML or XML routes.

Custom mapper. The objectMapper option and the camel.dataformat.jackson.object-mapper property take a Jackson 3 tools.jackson.databind.ObjectMapper, for example a JsonMapper.

Modules. camel.dataformat.jackson.module-class-names and module-refs must reference Jackson 3 modules (tools.jackson.databind.JacksonModule).

Features. In enable-features and disable-features, use plain feature names, or the Jackson 3 class name as the prefix. Some features moved to another class in Jackson 3, and the old prefix fails at startup:

# works on both Jackson 2 and Jackson 3
camel.dataformat.jackson.enable-features=WRITE_DATES_AS_TIMESTAMPS
# fails at startup on Jackson 3: the feature moved to DateTimeFeature
# camel.dataformat.jackson.enable-features=SerializationFeature.WRITE_DATES_AS_TIMESTAMPS

Reusing the Spring Boot mapper. Set camel.dataformat.jackson.auto-discover-object-mapper=true so routes use the JsonMapper that Spring Boot creates: routes and Spring MVC controllers then produce the same JSON, and spring.jackson. applies to both. Without it, Camel uses its own mapper and spring.jackson. has no effect on routes. Two things to know:

Error handling. Jackson 3 exceptions are unchecked and are not IOExceptions. Replace onException(IOException.class) and onException(JsonProcessingException.class) clauses that handle JSON errors with onException(tools.jackson.core.JacksonException.class).

Reuse the Spring Boot mapper (auto-discover-object-mapper=true) and set spring.jackson.use-jackson2-defaults=true. This also changes the JSON of your Spring MVC controllers.

Or give only Camel a mapper with Jackson 2 defaults, using a DataFormatCustomizer bean. The camel.dataformat.jackson.* properties are still applied on top of it:

@Bean
DataFormatCustomizer camelJackson2Defaults() {
    return DataFormatCustomizer.forType(org.apache.camel.component.jackson3.JacksonDataFormat.class,
            df -> df.setObjectMapper(JsonMapper.builderWithJackson2Defaults().build()));
}