I have a custom form for our patrons to subscribe to our email list, which has been working for a long time. As of today we cannot add new subscribers (post request) or update existing subscribers (put request) because we get the following error:   requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: https://api.cc.email/v3/contacts   Here is the post request with names and field ids changed to protect the innocent:   {'contact_data': {'create_source': 'Contact', 'custom_fields': [{'custom_field_id': '54ab04ba-b9f2-11ed-987c-fa163eb65cb7', 'value': ''}], 'email_address': {'address': 'ronaldaaronson@hotmail.com', 'confirm_status': 'off', 'permission_to_send': 'explicit'}, 'first_name': 'Ron', 'last_name': 'Aaronson', 'list_memberships': ['c175661c-b9e8-11ed-b3a8-fa163e0234d4'], 'phone_numbers': [{'kind': 'home', 'phone_number': ''}, {'kind': 'mobile', 'phone_number': ''}, {'kind': 'work', 'phone_number': ''}], 'street_addresses': [{'city': '', 'country': 'US', 'kind': 'home', 'postal_code': '', 'state': '', 'street': ''}]}, 'request_type': 'post', 'url': 'https://api.cc.email/v3/contacts'}   As an image with better formatting:     Any help is appreciated! ... View more