Hard to help without a MWE (please look at Please read: make it easier to help you)
That said, the error message seems clear - “Excel xlsx file; not supported”, so you are probably using an Excel reader that only allows reading xls format, not the newer xlsx format. I think the default reader used by pandas has recently dropped support for xlsx - here’s an SO question about it with suggested workaroudns: python - xlrd.biffh.XLRDError: Excel xlsx file; not supported - Stack Overflow