19011: Contact update failed: invalid JSON or non-updatable field

This error occurs when your contact update request contains invalid JSON or includes fields that this endpoint does not allow you to update. Update only first_name, middle_name, last_name, legal_name, preferred_name, unique_customer_provided_id, or custom_fields.

• The request body is not valid JSON.
• The request includes one or more fields other than first_name, middle_name, last_name, legal_name, preferred_name, unique_customer_provided_id, or custom_fields.
• The request mixes supported update fields with unsupported fields in the same payload.

• Validate the request body and send well-formed JSON.
• Remove any unsupported fields from the update request.
• Limit contact updates to first_name, middle_name, last_name, legal_name, preferred_name, unique_customer_provided_id, and custom_fields.
• Retry the request after you correct the payload.

• Contact API
• Compliance Toolkit for Programmable Messaging
• Debugging your Twilio application