Ha! I just solved it. I had three columns that looked blank, but the titles actually contained three spaces. I deleted the spaces and now the file will load.
Thanks for posting this - saved me some brain damage trying to figure out what was going on.
I'm getting this error too, but I've confirmed that there are no spaces in the headers. Still can't figure it out. It would be nice if the tool would identify the cell that is causing the issue. Any thoughts?
I had the same error, and I did the following to correct it (took the multi-prong attach approach):
1) Removed "returns" that were in front of several column headings, including the first two column headings (columns A and B in excel)
2) Used the "trim" function in excel for all my headings to remove any excess spaces.
3) Made sure all my data (line 2 of excel, right underneath the headings) contained actual data (numbers or letters) and not blanks or special characters.
4) I copied my data into a new excel workbook, and did paste special --> values only, so as to remove any formatting or other quirks.
After doing all of that, the file uploaded to tableau with out a problem.