
_xlfn. in excel is a prefix that appears, when a function is not recognized by your Excel version. This is usually happens when you enter a formula with a function which has been introduced in the later or newer versions of Excel, but the file is opened in an older version that does not support that function.
To understand this easily, I’m going to use the function TEXTJOIN which is introduced in the 2019 version but in the Excel 2013 which causes _xlfn. in the current version.

If a formula contains the TEXTJOIN function in the formula and it will display the _xlfn. in the formula bar.
=TEXTJOIN(", ", TRUE, B4:B7)
The above formula will be displayed normally in the newer version of the excel but in the older version the same formula will display _xlfn. with it.
=_xlfn.TEXTJOIN(", ", TRUE, B4:B7)
This means that Excel does not recognize TEXTJOIN in your version.
Function Name |
Function Usage |
Function Usage |
---|---|---|
TEXTJOIN |
Merges text strings with a delimiter |
Excel 2016 |
IFS |
Formula to have multiple conditions without nested functions |
Excel 2016 |
CONCAT |
Function used to replace CONCATENATE function for merging texts |
Excel 2016 |
XLOOKUP |
A powerful alternative Function to VLOOKUP and INDEX-MATCH |
Excel 2019 / 365 |
FILTER |
Function to filter an array based on the given criteria |
Excel 2019 / 365 |
UNIQUE |
Function to give the unique values in the range of area |
Excel 2019 / 365 |
https://support.microsoft.com/en-us/office/install-office-updates-2ab296f3-7f03-43a2-8e50-46de917611c5
=B4 & ", " & B5 & ", " & B6 & ", " & B7
The above manual formula will joins all the text with “,” comma delimiter without any function to do it.
That’s it.