Root-level contact fields
( first_name , last_name , email , mobile_phone )
must now be provided inside a primary_contact object, or as entries in the contacts array.
The notification_options field has been removed. Notification preferences are now managed at the contact level.
The fields bill_email , bill_email_cc , bill_email_bcc ,
and billing_address have been replaced by the bill_to object.
The shipping_address field has been replaced by the sold_to object.
Products → Items
The Products endpoint has been renamed to Items. Update requests to site/{site_id}/item/addUpdate instead of site/{site_id}/product/addUpdate .
Affecting
POST
{base_url}/api/v4/site/{site_id}/item/addUpdate
Attachments
The attachments field (a plain list of URLs) has been replaced by the attachment_refs object, which organises attachments into internal , external ,
and source_pdf sub-fields.