The Invalid Excel Import error is issued in the following situations:

Check your Excel file and make sure it contains at least one worksheet with column headers and rows with data to be loaded. See more about Creating Entities from an Excel File.

Edit your Excel file and move the column headers and their data to have the first column header starting at the A1 cell. See more about Creating Entities from an Excel File.

Import an unencrypted version of the Excel file.

See Also

Creating Entities from an Excel File | About Error Messages