Understanding the ISERR Formula

The ISERR function in Excel checks whether a value is an error of any type except #N/A, returning TRUE if it detects an error and FALSE otherwise. It's an error-checking tool for formula validation—like identifying calculation problems while allowing for specifically designated 'not available' values.

ISERR(A1) evaluates cell A1 and returns TRUE if it contains any error value except #N/A. It takes a value argument and performs targeted error detection—perfect for complex calculations where #N/A might be an expected or acceptable outcome but other errors indicate real problems.

Why Use ISERR?

ISERR enables specific error detection—think selective error handling or debugging. Its distinction between #N/A and other errors makes it valuable when working with lookup functions where #N/A is an expected result for certain inputs, while other errors indicate formula or data issues that need attention.

Example with Sample Data

ISERR identifies most errors: TRUE for #DIV/0!, #VALUE!, #REF!, #NAME?, #NUM!, and #NULL!, but FALSE for #N/A or non-errors. It's useful for creating formulas that treat #N/A differently from other errors. It's a selective error detector.