My prospect list won't upload - CSV contains bad data?

If you upload a list of prospects and receive an error that your file contains bad data, it's likely because you're uploading a spreadsheet file other than a comma separated file (.csv) like an excel file (.xls). Saving your file as a CSV file should do the trick here.

To save your spreadsheet as a CSV file:

In Excel: File-->Save As-->File Format: Comma Separated Values (.csv). This will just save the active sheet you are working on, whereas a .xls file is workbook that can contain multiple sheets.

In Google Sheets: File-->Download As-->comma-separated values (.csv, current sheet). This will just save the active sheet you are working on, whereas a .xls file is workbook that can contain multiple sheets.