ISERROR in Calligra Sheets: Detect Any Formula Error

• Introduced: Documented by 26.08.2; original introduction not established.
• Availability: Supported in Calligra Sheets 26.08.2, based on the function-specific registration.
• Scope: The official application listing provides Linux installation; other packaged builds are unverified here.
• Checked: October 14, 2026. Documentation/source check; no new native test in Calligra Sheets 26.08.2.

ISERROR tests whether its argument is any error value, including an N/A error. In Calligra 26.08.2 the callback is return Value(args[0].isError());. Unlike ISERR, this does not exclude N/A. [E1–E3]

Use it to flag faulty calculations before a summary is shared, not to silently discard problematic values. An empty cell, text label or valid number is not itself a formula error. When the original error matters for diagnosis, retain the raw result in a separate column and flag it rather than replacing it without a log. [E1–E4]

=ISERROR(x)

Exactly one required, position-1 argument x, declared as type Any by the release-pinned XML. Return type is Boolean. No optional arguments and no defaults appear in that function entry. The pinned information.cpp registers ISERROR near line 80 and defines Value(args[0].isError()) near lines 352–356. [E1–E3]

In a blank sheet, create four deliberately different result categories. Enter the following formulas/values in column A, enter =ISERROR(A2) into B2 and fill through B6. NA() is an officially registered zero-argument function returning an N/A error; =1/0 is a deliberately invalid division. [E1–E4]

Expected B2:B6: TRUE, TRUE, FALSE, FALSE, FALSE, conditional on the formula engine delivering those evaluated error values to the ISERROR callback. The callbacks and category predicates have been checked from sources; actual installation-specific error generation and propagation have not been observed. Do not claim the exact displayed error label for row 3 until native testing. [E1–E4]

Advanced example 1 — non-destructive exception queue

In C2, enter:

=IF(ISERROR(A2);"Review error";"No error")

Fill down. The predicted C2 and C3 are Review error, while C4 and C5 are No error. Preserve the untouched original formula in A2/A3, because ISERROR tells you only that an error exists, not its cause. No Calligra execution was performed. [E1–E4]

Advanced example 2 — partition errors by type

Use a third column (D2) to separate missing values from other errors:

=IF(ISNA(A2);"N/A";IF(ISERROR(A2);"Other error";"No error"))

The independently reasoned labels for A2==NA(), A3==1/0, A4=42 are N/A, Other error, No error, respectively, assuming normal error propagation. This is useful for a data-quality dashboard where missing measurements have different next steps from arithmetic failures. It is a prediction, not a native run. [E1–E4]

Compare the three error detectors

The table is source/definition-derived. ISERROR checks the error class, whereas ISERR and ISNA separately compare its error message against Calligra’s built-in N/A error message. These are distinct functions, not alias spellings. [E1–E4]

• N/A unexpectedly not flagged: confirm the value is an actual error, not literal text such as "#N/A". ISERROR tests Value::isError(), not the displayed characters. [E3]
• A broken formula masks the detector itself: one issue for native testing is whether the formula evaluator passes all errors to the predicate. Keep the original error column visible and investigate parser or calculation failures. [E3, E4]
• A valid zero returns FALSE: zero is a numeric value, not an error; distinguish it from division by zero. [E1, E3]
• A zero-length text result returns FALSE: source predicate rejects ordinary non-error values; unusual importer coercions still need native confirmation. [E3]
• N/A versus other errors: use ISNA to identify missing data specifically and ISERR for everything except N/A. Do not claim that ISERROR itself identifies which error occurred. [E1–E3]
• Locale-specific display: the error category matters more than an English glyph like #DIV/0!; do not rely on string comparison of rendered labels. [E1–E3]

Microsoft Excel and LibreOffice Calc both document ISERROR as TRUE for any error, including N/A. That makes the high-level intended meaning portable. However, their error token formats, formula-evaluation rules and import behavior are not proven identical to the examined Calligra release. Do not import error-handling formulas without testing the specific failure categories and source data types. [E1, E5]

Is ISERROR a repair function? No; it returns a Boolean. An IF expression can display a warning, but silently replacing errors can hide broken inputs. [E1–E3]

Does ISERROR include N/A? Yes. The Calligra handbook says any error, and the source checks isError() without excluding N/A. [E1–E3]

How is ISERROR different from IFERROR? ISERROR is a predicate. IFERROR is a replacement-style operation in products that implement it; verify platform/version-specific behavior separately. [E1, E5]

Calligra’s English reference uses a leading = for worksheet entry and a semicolon between arguments when a function needs several inputs. This function has one required argument, so its own syntax has no separator. The IF examples use ;; if your localized Calligra input configuration differs, use Insert → Function to verify separator entry. A displayed Boolean label or error message may be localized; compare the actual value category rather than translating a displayed error string. [E1, E2]

The implementation examined is the Calligra 26.08.2 function module at pinned commit 72123cc643f6625351139e7df294544255a1056f, associated with the 2026-10-08 release. The stable KF6 English handbook is an official description, not a log of this binary running on Linux, Windows or another platform. Calligra’s current KDE application page advertises a Linux install route; package availability and optional downstream patches can change. No installed Calligra application was available for native verification. [E1–E3, E6]

Validation taxonomy: DOC means an official handbook/XML statement; SOURCE means code inspected at the pinned revision; CALC means an independent truth-table or arithmetic check; EXPECTED means a predicted worksheet result. None of the displayed answers in these guides is a NATIVE_OBSERVED result. Recheck type-coercion, error propagation and localized displays before production use. [E1–E4]

• [E1 — KDE DOC] Official English Calligra Sheets function handbook, Information section for this named function and NA; accessed 2026-10-12. Official syntax, category and meanings.
• [E2 — KDE VERSION-PINNED XML] Calligra information.xml at 72123cc643f6, the exact <Function> entry. One Any argument, Boolean result and no declared optional parameter/default for this function; accessed 2026-10-12.
• [E3 — KDE VERSION-PINNED SOURCE] Calligra information.cpp at 72123cc643f6; corresponding Function registration and callback. Implementation observed in source, not a native run; accessed 2026-10-12.
• [E4 — INDEPENDENT LOGIC] The explicit input-type/error-category truth table shown above. Results calculated from Boolean predicates and documented error categories; not executed in Calligra.
• [E5 — COMPATIBILITY DOCS] Microsoft Excel IS functions and LibreOffice Calc information functions, both official vendor documentation, accessed 2026-10-12. Cross-product names and high-level meaning, not proof of identical parser/locale/runtime handling.
• [E6 — OFFICIAL RELEASE] KDE’s Calligra Sheets release listing, version 26.08.2 — October 8, 2026; accessed 2026-10-12.