My CSV won't import into my store, or I get an "Uploaded file must be of type 'csv'" error

This is almost always a file-handling quirk on your computer or browser, not a problem with the file itself.

Things to try:

Do not open the file in Excel and re-save it. Excel can change the format or save it as a different file type. Upload the CSV exactly as Product Upload generated it.
If you see must be of type 'csv', try a different browser. Firefox in particular can mislabel the download's file type, while Chrome or Edge usually upload it cleanly.
Make sure you are using the importer that matches your platform. BigCommerce and WooCommerce each expect their own CSV format, so download the version for your platform from the Publish menu.

Still stuck? Send us the exact error message and the CSV, and we'll check whether it is a formatting issue on our end.

Updated on: 31/05/2026

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