Unrecognized field "X" (class Y), not marked as ignorable

The fix

Add @JsonIgnoreProperties(ignoreUnknown = true) to the class, as in the fixed code. If the key was renamed, add or rename the field instead.

{
  "id": 7,
  "status": "shipped",
  "carrier": "DHL"
}

public class Order {
  public long id;
  public String status;
}

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

@JsonIgnoreProperties(ignoreUnknown = true)
public class Order {
  public long id;
  public String status;
}

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

How the message appears

Only a plain Jackson 2 ObjectMapper throws this, so there is one error and where it stopped. Jackson 3 and Spring 6.2 and 7.0 read the same JSON and skip the unknown key.

What causes it

1. 1

   The sender added a field

   The other side added a field and your class has not caught up. The message tells you both sides: the key it did not know, "carrier", and the ones it does, (2 known properties: "status", "id").

2. 2

   A misspelled or renamed key

   If the JSON says carrier and your field is shipper, Jackson cannot match them. Compare the unknown key with the known properties in the message.

3. 3

   It works in Spring but fails in your test

   Jackson 3 and Spring 6.2 and 7.0 read this same JSON and skipped carrier. Only a plain Jackson 2 ObjectMapper threw. So a test that creates its own new ObjectMapper() fails while the app works. See the Spring page.

Worth knowing