If are working in Excel 2010 or higher, it's possible that the CSV was saved under a different CSV file format that Luminate does not recognize. The file must be saved in the CSV (Comma Delimited) file type. Re-save the file in this format and attempt the import once more.
If this does not address the error, it's possible that the file has become corrupted in some way. Transfer the data to a fresh .csv file, save it under the correct format and re-attempt the operation.
If are still unable to successfully commit the operation, <a href="https://www.blackbaud.com/support/needhelp.aspx">Contact Support</a> and provide this article number.