An _xlfn. prefix is displayed in front of a function in a formula. When the formula is calculated, it displays the #NAME? error value.
The Excel workbook contains a function that is not supported in the version of Excel that you are currently running. For example, you may have opened a workbook that contains the IFERROR function, which is not supported in versions of Excel earlier than Excel 2007. Functions that are not supported in versions of Excel earlier than Excel 2007 include: AVERAGEIF, AVERAGEIFS, MAXIFS, MINIFS, IFS, CUBEKPIMEMBER, CUBEMEMBER, CUBEMEMBERPROPERTY, CUBERANKEDMEMBER, CUBESET, CUBESETCOUNT, CUBEVALUE, COUNTIFS, IFERROR, and SUMIFS.
Remove the unsupported functions, or if possible, replace the unsupported functions with supported functions.