SpringBoot SpringBoot 4.0.0-M2 to SpringBoot 4.0.0-M3, regression? Consider defining a bean of type 'com.fasterxml.jackson.databind.ObjectMapper' in your configuration.

Hello Spring team,

How are you?

Sorry to trouble you with this issue.

We just bumped our SpringBoot 4.0.0-M2 to M3, no code change, basically, the entire change is just to change one digit.

We have a Service class which looks like:

    private final WebClient webClient;
    private final ObjectWriter objectWriter;

    public MyService(final WebClient client, final ObjectMapper mapper) {
        this.webClient = client;
        this.objectWriter = mapper.writer();
    }

Everything is working fine with M2.

Just bumped to M3, nothing else, and getting Consider defining a bean of type 'com.fasterxml.jackson.databind.ObjectMapper' in your configuration.

IntelliJ IDE also mentions the "Could not auto wire. No beans of 'ObjectMapper' type found. just for M3

May I ask if there is a regression in the code?

Thank you for your time and help.

Good day!

Comment From: bclozel

Hello @patpatpat123

As of Spring Boot 4.0.0-M3, we now depend and auto-configure Jackson 3.0 exclusively. You should now inject tools.jackson.databind.json.JsonMapper and review Jackson's usage in your application accordingly.

For a complete guide, see the Jackson migration docs.

Comment From: patpatpat123

Thank you @bclozel . Good day!

Comment From: bclozel

@patpatpat123 in the meantime we published this: https://spring.io/blog/2025/10/07/introducing-jackson-3-support-in-spring