Cannot write required AWS Cognito attribute – Amazon web services

I created a user pool in AWS’s Cognito, specified given_name and family_name as required user attributes. I also added an app and checked the permissions :

If – using the Cognito Identidy SDK – I try to register a user and omit the attributes, I get: "Attributes did not conform to the schema: given_name: The attribute is required family_name: The attribute is required" which is expected.

If I include the attributes:

const firstNameAttribute = new CognitoUserAttribute({ Name: 'first_name', Value: firstName });
const lastNameAttribute = new CognitoUserAttribute({ Name: 'last_name', Value: lastName });
cognitoUserPool.signUp(username, password, [firstNameAttribute], [lastNameAttribute], callback);

The server returns

{
    "__type":"NotAuthorizedException",
    "message":"A client attempted to write unauthorized attribute"
}

How can I fix this and let users set their name during registration?