Books API error 3044: "email address can not be blank for contacts associated to recurring invoices"

Hi, I am having this issue but do not understand why.

I get this error when I try to update contact in Books

Example:

params: {"JSONString":{"contact_name":"CUSTOMER NAME","currency_id":"xxxxxxxxx","phone":"11111111111","billing_address":{"address":"ppppppppppppp","state":"DDDDDDDDDDD","city":"cccccccccccccc","zip":"sssssss"},"contact_type":"customer","custom_fields":[{"api_name":"cf_rut","value":"111111111111111"},{"api_name":"cf_raz_n_social","value":"DDDDDDDDDDD"},{"api_name":"cf_c_digo_iso","value":null}],"contact_persons":[{"email":"mail@server.com"}]}}

response = invokeurl

[

url :"https://books.zoho.com/api/v3/contacts/{accidBooks}?organization_id=" + id

type :PUT

parameters:params

connection:"xxxxxxxxxxxx"

];

I confirm that contact has recurring invoice but the contact associated with that invoices has a valid email address

Error response:

{"code":3044,"message":"El correo electrónico no puede estar en blanco para los contactos que estén asociados con alguna factura recurrente."}