ISERROR Function

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The Excel ISERROR function tests whether a value is any error. It returns TRUE or FALSE, making it the building block of error-proof formulas, validation, and conditional logic.

Quick answer: test a cell:
=ISERROR(A2) // TRUE when the value is any error (#N/A, #VALUE!, #REF!, #DIV/0!, etc.)

Syntax

=ISERROR(value)
ArgumentDescription
valueRequiredThe value, cell, or expression to test.

How to use it

ISERROR returns TRUE when the value is any error (#N/A, #VALUE!, #REF!, #DIV/0!, etc.), and FALSE otherwise. Wrap it in IF to act on the result, or sum it with SUMPRODUCT to count matches: =SUMPRODUCT(--ISERROR(A2:A100)).

The IS family: ISBLANK, ISNUMBER, ISTEXT, ISLOGICAL, ISNONTEXT, ISERR, ISERROR, ISNA, ISREF, ISFORMULA, ISEVEN, and ISODD each return TRUE or FALSE so you can branch with IF, count with SUMPRODUCT, or drive conditional formatting.

Try it: interactive demo

Live demo

Pick an input and watch the formula and result update.

Result:

Practice workbook

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Frequently asked questions

ISERROR vs IFERROR?
IFERROR both tests AND replaces in one step: =IFERROR(formula,"fallback"). ISERROR only returns TRUE/FALSE. Prefer IFERROR for clean error handling.
ISERROR vs ISERR?
ISERROR catches all errors; ISERR catches all EXCEPT #N/A. Use ISERR when a missing-lookup #N/A should pass through.
How do I act on the TRUE/FALSE result?
Wrap it in IF: =IF(ISERROR(A2), "yes", "no").
Can I count how many cells pass?
Yes: =SUMPRODUCT(--ISERROR(range)) counts the TRUEs.

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Related functions: ISERROR · ISNUMBER · ISBLANK · IFERROR · NA