Error Code 21919303
The item specific is missing. Add item specific to this listing, enter a valid value, and then try again. An item specific has not been entered for your item. (ITEM SPECIFICS can be brand, material, style, MPN etc.)
Many categories on eBay now require this field to be completed before a listing can be successfully submitted. After entering a valid value to the item specific field, force a product data update to resolve the problem.