CSV Upload Error: Illegal character/ string - How to save as plain CSV for import

If receiving this error in your Upload History, verify that you saved your spreadsheet as a plain CSV (not UTF-8)

Certain UTF-8 characters may also present an error in a plan CSV format.

The most common is a start or end of guard character:

replace – or — with a minus: -

Normal special characters on a standard keyboard are acceptable ($,%,&,<,* etc)