Try each of the following steps until the issue/error is resolved:
  • Ensure headers are included in the file and they start with a letter and contain only letters, numbers and underscores
  • Remove invalid characters from the imported list.  The "@" symbol and periods (".") & Underscores ("_") are allowed, as are date values with a slash ("/") character.
  • Ensure that each field within the file contains a value in each row.
  • Ensure each column has a header. The header must be alphanumeric, and cannot contain any special characters.
  • Delete any columns that you don't need. Columns that you need are Email address, Name, and any other things you want to use as merge fields.

How to remove hidden characters:
  1. Copy (CTRL+C) the necessary contents from the top-left to the bottom-right (where data exists).
  2. Open Notepad. Paste the contents into Notepad. Save the file as a regular .txt document. [Notepad removes hidden characters and formatting so it is a safe program to start over in]. Highlight the contents in the file (CTRL+A) and copy them (CTRL+C).
  3. Go back to Excel. Create a new workbook. Save the file as a .csv document.
  4. Click the top-left area of the spreadsheet between the letter A and the number 1. Paste the contents (CTRL+V) and save the file again.
  5. Go to your NetCommunity site and try to upload the file again.