Error: dynamodb could not instantiate class

Could not instantiate class means the Java mapping layer failed to construct a model instance. Read the deepest exception: a missing accessible constructor, a non-static inner class or code throwing inside the constructor requires a different repair.

1. For a mutable bean model, supply an accessible no-argument constructor and matching public getter/setter methods.
2. Make nested model classes static so they do not require an enclosing instance. The class being in the same source file is not itself an error.
3. Check that the mapped type is concrete and that its constructor does not throw. Verify generated Lombok constructors and accessors.
4. For the Java v2 Enhanced Client, use @DynamoDbBean with TableSchema.fromBean, or deliberately choose an immutable or static schema instead.

@DynamoDbBean
public class Person {
    private String id;
    public Person() {}
    @DynamoDbPartitionKey
    public String getId() { return id; }
    public void setId(String id) { this.id = id; }
}

The annotations shown are from software.amazon.awssdk.enhanced.dynamodb.mapper.annotations. Legacy v1 DynamoDBMapper uses different annotations. Adding a no-argument constructor helps bean construction but does not repair a stored value that a converter cannot parse.

See Java models and AWS documentation.