My order import says some rows failed. How do I find out why?

After you click Import, the import window shows a summary like "Imported 40 · Failed 3". Under it, each failed row is listed as "Row N" with the reason. The first eight are shown.

The most common reason is Missing customer name/email. Every row needs a name or an email. Row numbers count your data rows from 1, not counting the header.

To fix it, correct only the failed rows in your spreadsheet, save them as a new CSV and import that file. The rows that already worked are saved, so don't import them again or they'll be created twice.