Using the Excel ISNA Function

Summary
The Excel ISNA function will return TRUE when a cell contains the #N/A error. FALSE is returned for any other value or error type. ISNA can be used with the IF function to test for errors and return a custom message.Syntax
=ISNA (Value)Syntax Breakdown
ValueRequired. A value that will be tested for the #N/A error. Typically supplied as a reference.
Usage Notes
ISNA will check if a cell contains the #N/A error. If a cell does contain the #N/A error, the function returns TRUE. In all other cases, the function returns FALSE.ISNA is considered one of Excel's IS functions, which are used to test for errors.
If you have Windows 2013+, use the IFNA function to identify and handle #N/A errors.
ISNA With IF
Use the ISNA function with the IF function to identify errors and return a custom message.
