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IFERROR vs ISERROR: handling vs detecting errors in Excel and Sheets
Excel & Google Sheets
=IFERROR(VLOOKUP(A2,B2:C5,2,0),"Not found")✓
Verified example
Computed by a real spreadsheet engine on the sample data below.
| Key | LookupVal | Price |
| Apple | Apple | 1.20 |
| Banana | Banana | 0.50 |
| Cherry | Mango | 2.00 |
| Durian | Orange | 0.80 |
=IFERROR(VLOOKUP(A2,B2:C5,2,0),"Not found")→1.2
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Step by step
- 1Put a lookup key in A2 and a lookup table in B2:C5 (lookup values in B, results in C).
- 2Wrap the VLOOKUP with IFERROR to return a fallback if the key is missing: =IFERROR(VLOOKUP(A2,B2:C5,2,0),"Not found"). If VLOOKUP finds a match, its result passes through; if it errors, "Not found" appears.
- 3Use ISERROR when you need to branch to completely different logic: =IF(ISERROR(VLOOKUP(A2,B2:C5,2,0)),"Missing","OK"). ISERROR returns TRUE for any error type (#N/A, #VALUE!, #REF!, etc.).
- 4To catch only #N/A (missing lookup), prefer IFNA over IFERROR — it leaves other error types visible so genuine formula mistakes are not silently hidden.
- 5For more granular detection, ISERR catches all errors except #N/A; use it when a #N/A is meaningful and should propagate, but other errors need handling.
Tips
- IFERROR can mask real formula bugs — if a formula has a logic error that produces #VALUE!, IFERROR will silently swallow it. During development, remove IFERROR wrappers to confirm the inner formula is correct.
- ISERROR inside IF is two function calls where IFERROR is one; use IFERROR when the goal is a fallback value, and reserve ISERROR for genuine branching where the two paths produce structurally different outputs.
- Both IFERROR and ISERROR are available in all current Excel and Google Sheets versions; IFNA requires Excel 2013+ and is always available in Sheets.
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Frequently asked
What is the difference between ISERROR and ISERR?
ISERROR returns TRUE for all error types including #N/A. ISERR returns TRUE for all errors except #N/A. Use ISERR when a missing-lookup result is semantically different from a formula mistake.
Does IFERROR evaluate the formula twice?
In older Excel versions it could. Modern Excel and Google Sheets evaluate the expression only once, so there is no performance penalty for using IFERROR over IF(ISERROR(...)).
Can IFERROR be nested?
Yes, but deeply nested IFERROR calls become hard to read. If you need to try multiple fallback lookups, consider IFERROR(VLOOKUP(...),IFERROR(XLOOKUP(...),"Default")) or restructure with XLOOKUP's built-in if-not-found argument.