ISERR in Calligra Sheets: Flag Errors Except N/A

ISERR distinguishes non-N/A errors from an N/A missing-value error. It returns TRUE for an error other than N/A and FALSE for N/A or a valid value. Its 26.08.2 callback checks isError() and that the error message differs from Value::errorNA().errorMessage(). [E1–E3]

Suppose an inventory feed deliberately marks an unavailable item as N/A, but you still want to catch broken arithmetic in landed-cost formulas. ISERR is the right category test: it excludes missing-value markers while flagging other errors. Do not treat an N/A as a valid numeric result; it is merely excluded by this specific predicate. [E1–E4]

=ISERR(x)

x is the sole required argument, of XML type Any; there are no optional arguments/defaults. The return is Boolean. In information.cpp, it is registered near line 78 and the callback at lines 346–350 returns isError() && errorMessage()!=errorNA().errorMessage(). It is not an alternate name for ISERROR; its N/A handling differs. [E1–E3]

Enter the following test data in column A, then put =ISERR(A2) in B2 and fill down through B6. This keeps the exceptional and unexceptional values visible for diagnosis. [E1–E4]

Expected B2:B6: FALSE, TRUE, FALSE, FALSE, FALSE if the error values reach the registered callbacks. The special difference in the N/A row is asserted by both KDE documentation and the source; the row 3 error path is still not natively tested. [E1–E4]

Advanced example 1 — separate missing from broken

In C2, enter and fill down:

=IF(ISERR(A2);"Fix calculation";IF(ISNA(A2);"Missing";"No detected error"))

Predicted labels: A2 → Missing; A3 → Fix calculation; A4 → No detected error. This stops a missing data marker from being confused with a formula that divides by zero, assuming standard evaluation of the input error values. Because the native evaluator has not been run, these are expected labels, not observed results. [E1–E4]

Advanced example 2 — preserve a calculation audit column

Instead of overwriting the original formula in A3, leave it visible and build a status cell beside it:

=IF(ISERR(A3);"Needs arithmetic review";"Not a non-N/A error")

For A3==1/0, the expected status is Needs arithmetic review. This does not make the input safe and does not establish that an N/A cell is acceptable; check ISNA as a separate branch when missing values also matter. [E1–E4]

Three-detector truth table

This table is derived from three distinct pinned callbacks and corroborated by the handbook; locale-specific error text should not be substituted as an argument. [E1–E4]

• N/A shows FALSE: this is by design, not a malfunction. Use ISERROR to flag N/A too. [E1–E3]
• A text value "#N/A" shows FALSE: literal text is not a Value error. Enter =NA() to create the native error marker. [E1–E3]
• Result seems inverted versus ISERROR: ISERR deliberately omits N/A. If all errors matter, choose ISERROR instead. [E1–E3]
• A division error causes a different displayed token: the predicate is based on error category, not a particular localized string. Exception wording may vary across spreadsheet engines and locales. [E3]
• Row reference changed while filling down: enter formula in B2, then fill through B6; ensure A2/A3 are not accidentally overwritten. [E4]
• Error apparently propagates instead of returning Boolean: test the native Calligra evaluator; the source-level callback alone does not prove every parser/evaluator pathway passes errors through. [E3, E4]

Excel and LibreOffice Calc officially document ISERR as excluding #N/A, matching the Calligra handbook and callback at the categorical level. LibreOffice gives a =1/0 example and an =NA() example. This is not a guarantee that all engines encode every error message alike or treat imported errors the same; retest after file migration. [E1, E5]

Why is ISERR false for NA()? It intentionally excludes N/A to let you distinguish missing values from other failures. [E1–E3]

Should I use ISERR or ISERROR? ISERR for only non-N/A errors; ISERROR if every error category is important. [E1–E3]

Can ISERR fix broken formulas? No. It supplies a TRUE/FALSE classification, not a corrected calculation. [E3]

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.