What's the difference between ISERROR and ISERR?

ISERROR catches all error types (#N/A, #REF!, #VALUE!, #DIV/0!, #NAME?, #NUM!, #NULL!, #SPILL!, #CALC!). ISERR catches all except #N/A, making it slightly more specific. Use ISERROR for broad error checking and ISERR when you want to allow #N/A as a distinct case.

Should I use ISERROR or IFERROR?

If you just need to detect an error, use ISERROR. If you want to replace the error with a fallback value or message, use IFERROR—it's shorter and clearer. Example: use IFERROR(VLOOKUP(...), "Not found") instead of IF(ISERROR(VLOOKUP(...)), "Not found", VLOOKUP(...)).

Can ISERROR detect errors in other worksheets?

Yes. ISERROR checks the result of any formula or cell reference, regardless of worksheet. Use =ISERROR(Sheet2!A1) or =ISERROR(VLOOKUP(..., Sheet2!A:E, 4, FALSE)) to test values on other sheets.

Why does ISERROR return FALSE for blank cells?

Blank cells are not errors in spreadsheet logic—they're simply empty values. ISERROR only returns TRUE for actual error values. To check for blanks, use ISBLANK(A1) instead. You can combine both: =IF(ISBLANK(A1), "Empty", IF(ISERROR(A1), "Error", "Valid")).

ISERROR function

ISERROR returns TRUE if a value is an error like #N/A or #REF!, FALSE otherwise, enabling error detection and handling.

=ISERROR(value)

Generate a ISERROR formula

Describe what you need. The generator will reach for ISERROR where ISERROR is the right tool, and tell you when it is not.

Arguments

How ISERROR reads its arguments

Argument	Required	Description
value	Required	Any cell, formula result, or expression to test. ISERROR checks whether it evaluates to an error value.

Returns

Boolean (TRUE or FALSE)

Availability

Excel: All · Google Sheets: Supported

Worked examples

1. Detect a failed student lookup

Student	Subject	Assignment	Score	MaxScore
Alice	Math	Quiz 1	85	100
Alice	Math	Quiz 2	92	100
Bob	Math	Quiz 1	78	100
Bob	Math	Quiz 2	88	100

=ISERROR(VLOOKUP("Charlie", A2:E5, 4, FALSE))

Result: TRUE

The VLOOKUP searches for Charlie in the Student column but finds no match, returning #N/A. ISERROR detects this error value and returns TRUE, signaling the lookup failed.

2. Check for division by zero in grade percentage

Score	MaxScore
85	100
92	100
78	100
88	100
0	0

=ISERROR(A6/B6)

Result: TRUE

Row 6 has a MaxScore of 0. Dividing Score (0) by MaxScore (0) produces #DIV/0!. ISERROR recognizes this error and returns TRUE.

3. Validate assignment scores before calculating average

Student	Subject	Assignment	Score
Alice	Math	Quiz 1	85
Alice	Math	Quiz 2	92
Bob	Math	Quiz 1	78
Bob	Math	Quiz 2	88

=IF(ISERROR(AVERAGE(D2:D5)), "Data error", AVERAGE(D2:D5))

Result: 85.75

ISERROR checks if AVERAGE produces an error. Since all scores are valid numbers, AVERAGE succeeds and returns 85.75. ISERROR returns FALSE, so the IF displays the average.

Common errors

Which ISERROR error are you seeing?

Error	Why it happens	How to fix it
#NAME?	Misspelling the function name, such as =ISSERROR(A1) or =ISERROR2(A1), causes Excel/Sheets to not recognize the function.	Verify the spelling: the correct function is ISERROR (not ISSERROR, ISERRORS, or similar variants).
#VALUE!	Omitting the required value argument entirely, such as =ISERROR(), leaves the function without data to evaluate.	Provide the value to check: =ISERROR(A1) or =ISERROR(VLOOKUP(...)) with a cell reference or formula.
#REF!	If the value you're testing contains a reference to a deleted column or row (e.g., =ISERROR(A1:A999) where rows were deleted), the reference breaks.	Restore the deleted row or column, or update the reference range to only include existing cells (e.g., =ISERROR(A1:A50)).

Tips and when to use something else

Use ISERROR to branch logic: combine with IF to show a default value or message when an error occurs, like =IF(ISERROR(...), "N/A", value).
For cleaner code, use IFERROR instead of nesting ISERROR inside IF—IFERROR directly replaces errors without extra wrapping.
ISERROR detects all error types (#N/A, #REF!, #VALUE!, #DIV/0!, #NAME?, #NUM!, #NULL!), so it's a catch-all for any error your formulas produce.
Consider ISNA if you only care about #N/A errors, or ISERR to catch all errors except #N/A—they're more specific when you don't need to trap every error type.

Related functions

IFERRORIFERROR returns the result of a formula unless that formula generates an error, in which case it returns a user-specified alternative value.ISNAISNA detects whether a value is the #N/A error, typically returned when a lookup function fails to find a match.ISERRISERR returns TRUE for spreadsheet errors (like #DIV/0! or #REF!) but not #N/A, helping you trap formula calculation failures.IFThe IF function returns one value if a condition is true and another (or nothing) if it is false, letting you branch logic in a cell.VLOOKUPVLOOKUP searches the first column of a table and returns a value from a specified column in the same row, optionally using exact or approximate matching.

Frequently asked questions

What's the difference between ISERROR and ISERR?: ISERROR catches all error types (#N/A, #REF!, #VALUE!, #DIV/0!, #NAME?, #NUM!, #NULL!, #SPILL!, #CALC!). ISERR catches all except #N/A, making it slightly more specific. Use ISERROR for broad error checking and ISERR when you want to allow #N/A as a distinct case.
Should I use ISERROR or IFERROR?: If you just need to detect an error, use ISERROR. If you want to replace the error with a fallback value or message, use IFERROR—it's shorter and clearer. Example: use IFERROR(VLOOKUP(...), "Not found") instead of IF(ISERROR(VLOOKUP(...)), "Not found", VLOOKUP(...)).
Can ISERROR detect errors in other worksheets?: Yes. ISERROR checks the result of any formula or cell reference, regardless of worksheet. Use =ISERROR(Sheet2!A1) or =ISERROR(VLOOKUP(..., Sheet2!A:E, 4, FALSE)) to test values on other sheets.
Why does ISERROR return FALSE for blank cells?: Blank cells are not errors in spreadsheet logic—they're simply empty values. ISERROR only returns TRUE for actual error values. To check for blanks, use ISBLANK(A1) instead. You can combine both: =IF(ISBLANK(A1), "Empty", IF(ISERROR(A1), "Error", "Valid")).

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Reviewed 2026-09-17