I don’t think spaces or dots should be a problem there. The problem is more that the names need to match the names that the csv importer expects (so as the csv export uses)
That is correct, but I had a dot in the headername: prijs_incl.BTW#
it came back in the error message with: ‘prijs_incl.BTW’#
the conversion in excel from xlsx to csv didn’t add the quotes.