This UDF is now part of AutoIt since 3.3.12.0. New versions of Microsoft Office have been released since the last changes were made to the Excel UDF. The new extensions (e.g. xlsx) are not (fully) supported, new functions are missing etc.   The rewrite of the Excel UDF delivers changes in the following areas: Works with as many instances of Excel as you like - not just one Works with any Workbook - not just the active one Works with any Worksheet - not just the active one Only does what