The headers in your file are invalid or the file is empty
This error appears when UpSheets cannot process your file because the first row does not contain the expected header fields.Check your file
Open your file in a text editor (not Excel) to check it looks correct and is not empty. Depending on how your file was created, opening it in Excel and saving it as CSV again may resolve some errors. The usual cause is text in the first line when UpSheets is expecting header fields separated by commas.Correct format
The first row must contain header fields only:Incorrect format
Extra text before the headers will cause the error:How to fix it
Remove the first line and save the file, then try again.Including notes in your file
If you want text lines in your file (such as notes) but do not wish to import them, put a# at the start of the line and it will be ignored: