19003: Contact with the unique_customer_provided_id provided already exists

This error occurs when you submit a contact with a unique_customer_provided_id that already belongs to an existing contact. Use unique_customer_provided_id as a unique identifier for one contact only. If you identify contacts from your own system with this field, keep that value mapped to a single contact record.

• You created a contact with a unique_customer_provided_id that is already assigned to another contact.
• You updated a contact and changed unique_customer_provided_id to a value that already exists on a different contact.
• Your application sent more than one contact record for the same external customer identifier, so multiple contacts attempted to use the same unique_customer_provided_id.

• Find the existing contact that already uses the unique_customer_provided_id. If the request refers to the same person, update that contact instead of creating another one.
• If the request is for a different person, send a different unique_customer_provided_id that is unique in your source system.
• If the existing contact is no longer needed, remove or update that contact before you retry the request.
• Review your contact sync logic so each external customer record maps to only one unique_customer_provided_id.

• Contact API
• Compliance Toolkit for Programmable Messaging
• Twilio Debugger