Hi Nam Ta
This is very common error when you are passing a value in JSON that doesn't exit on the API Pages or the name that you have put in JSON is wrong.
Please check all of the fields are available in the sales order API page and with same name. customerNumber, OrderDate etc.
You can also test it by passing only the customerNumber and see if it is inserting the record or not. If it gets inserted then your JSON has some field thats not available on the API page.
{
"customerNumber": "1728",
"orderDate": "2023-05-30",
"postingDate": "2023-05-30",
"billToCustomerNumber": "1728",
"sellToAddressLine1": "BLK 704 ANG MO KIO AVENUE 8",
"sellToAddressLine2": "#01-2559",
"sellToCity": "",
"sellToState": "",
"sellToCountry": "",
"sellToPostCode": "560704",
"shipToAddressLine1": "BLK 704 ANG MO KIO AVENUE 8",
"shipToAddressLine2": "#01-2559",
"shipToCity": "",
"shipToState": "",
"shipToCountry": "",
"shipToPostCode": "560704"
}