Java 8 date/time type java.time.LocalDateTime not supported by default

The fix

On Jackson 2, add the jackson-datatype-jsr310 dependency and register the module once on the mapper: mapper.registerModule(new JavaTimeModule());. On Jackson 3 you need nothing.

{
  "id": 7,
  "createdAt": "2026-10-14T09:30:00"
}

public class Order {
  public long id;
  public LocalDateTime createdAt;
}

Order order = mapper.readValue(json, Order.class);

public class Order {
  public long id;
  public LocalDateTime createdAt;
}

mapper.registerModule(new JavaTimeModule());
Order order = mapper.readValue(json, Order.class);

How the message appears

Only a plain Jackson 2 ObjectMapper throws this, so there is no Jackson 3 or Spring line. First the error when reading, with where it stopped. Then the same error when writing, which has no position because nothing is being read.

What causes it

1. 1

   A plain new ObjectMapper on Jackson 2

   new ObjectMapper() on Jackson 2 has no handler for LocalDateTime. The message names the module to add, jackson-datatype-jsr310. The JSON is fine.

2. 2

   Writing fails too

   It is not only reading. Writing an Order with a LocalDateTime through the same mapper throws the same message. That one has no at [Source: ...] part, only the field: com.example.Order["createdAt"].

3. 3

   It works in Spring but fails in your test

   With jackson-datatype-jsr310 on the classpath, Spring's converter read this JSON with no error. A mapper you create yourself with new ObjectMapper() does not. So a unit test or a helper class can fail while the app works. See the Spring page.

4. 4

   Jackson 3 does not have this problem

   Jackson 3 reads LocalDateTime with no module and no setup, and so does Spring 7. If you see this error, it comes from Jackson 2.

Worth knowing