Cannot deserialize value of type X from Array value

The fix

Read it as a list: List<Order> orders = mapper.readValue(json, new TypeReference<List<Order>>() {});. If the API is supposed to send one order, fix the sender instead.

[
  { "id": 1, "status": "shipped" },
  { "id": 2, "status": "pending" }
]

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

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

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

List<Order> orders = mapper.readValue(json, new TypeReference<List<Order>>() {});

How the message appears

Jackson 2, then Jackson 3, then Spring (the same on 6.2 and 7.0). The last line is the opposite mistake: one object read into a List.

What causes it

1. 1

   A list read into one object

   Look at the first character of the JSON. [ is a list and { is one object. Here it is [, and Order.class asks for one object. Jackson tells you both: the type you asked for, and the token it found, JsonToken.START_ARRAY.

2. 2

   The API started sending a list

   Code written for one record breaks when the other side starts sending several. The JSON is still valid, so nothing looks wrong until you read it. Check what the API says it returns.

3. 3

   The opposite: one object where you expected a list

   Read a single object into List<Order> and you get the same message the other way round: from Object value and JsonToken.START_OBJECT. The type shows as java.util.ArrayList<com.example.Order>.

4. 4

   Spring does not say where

   Spring wraps it as JSON parse error: Cannot deserialize value of type, then the type and from Array value, without the at [Source: ...] line. The type in the message is the type of your request body. Other Spring messages are on the Spring page.