Information
ISERR function: detect broken math errors (#DIV/0!, #VALUE!) while ignoring #N/A
Separate broken calculation errors from expected #N/A missing-lookup markers using ISERR vs ISERROR.
How ISERR differs from ISERROR and ISNA
Spreadsheets provide three error-testing functions with complementary coverage: ISNA catches ONLY #N/A; ISERR catches EVERY error EXCEPT #N/A (#DIV/0!, #VALUE!, #REF!, #NAME?, #NUM!, #NULL!); and ISERROR catches ALL errors including #N/A.
Use ISERR in audit columns when #N/A is an intentional chart placeholder (from NA()) or handled separately, so you alert only on genuine broken formulas.
| Cell | Formula / Value | ISERR | ISNA | ISERROR |
|---|---|---|---|---|
| B2 | =100 / 0 (#DIV/0!) | TRUE | FALSE | TRUE |
| B3 | =NA() (#N/A) | FALSE | TRUE | TRUE |
| B4 | 250 (valid number) | FALSE | FALSE | FALSE |
Flag broken arithmetic while letting #N/A pass
ISERR(B2) returns TRUE on #DIV/0!, while ISERR(B3) returns FALSE on #N/A.
=ISERR(B2)Verify complementary identity ISERR + ISNA = ISERROR
For any cell X, OR(ISERR(X), ISNA(X)) always equals ISERROR(X).
=OR(ISERR(B3), ISNA(B3)) = ISERROR(B3)Try the example
Use the original values or change them to test your understanding.