The error message "Harmonized code is invalid" concerns international shipments when there is an issue in the HS code input and the carrier systems rejected to generate label.
"Harmonized code is invalid" error usually occurs when the HS code format is wrong or there is a symbol or sign such as 「...」, ＃, etc. input in the HS code. HS code is not mandatory by the system specification but you will require to input it correctly in at least 6-digit number. Please follow this rule with you set up your account.
When registering the Product Type in Product Type lists in Ship&co Settings page, if you leave the HS code input blank, the system will generate the random code 'EMPTY-****'. You can print the label with that code, but we highly recommend you to use HS code only with numbers to make the parcel pass custom process smoothly.