I've seen this come up many times, especially with people new to Yahoo! Store. They try to use the database upload function to load products into the store, and get a bunch of error messages after the upload complaining about missing fields, invalid characters, etc. The problem most likely is that they are trying to upload the actual Excel (XLS) file, not a CSV file. So before you try to upload your spreadsheet, first make a copy of it as a CSV file. This is one of the file type formats when you select File > Save As in Excel. Then, upload the CSV copy, not the original Excel file. Here is some more info on the database upload feature for Yahoo! Store .