The Excel Error Index 2026

The workbook uses XLOOKUP, VSTACK, FILTER, TEXTSPLIT or another function that does not exist in the submission machine's Excel version.

Symptom: A modern function works on one machine and fails on another.

First fix: Check File → Account → About Excel. Rebuild with functions available in that version, or add a Power Query / INDEX-MATCH fallback.

Rates, thresholds, years or totals are embedded in formulas, so the model cannot be audited, updated or defended when an input changes.

Symptom: Numbers are typed inside formulas instead of living in input cells.

First fix: Move every assumption to a labelled input cell, then reference it with an absolute address such as $B$4.

The classic causes are a missing FALSE in VLOOKUP, an approximate MATCH, a column index that shifted after an insert, or a lookup range that excludes the last row.

Symptom: A lookup returns the wrong row, a shifted column or a plausible but incorrect value.

First fix: Use exact-match VLOOKUP/XLOOKUP, bound the range, and test a value that should not be found.

Imported CSV files, copied web tables and manually typed columns leave trailing spaces, text-numbers, mixed date formats and duplicates that formulas cannot reconcile.

Symptom: Numbers are stored as text, dates are text, or duplicate rows inflate a total.

First fix: Trim, convert types, remove duplicates and check the row count before building the summary.

A reference that should stay fixed is relative, so the lookup table, tax rate or total range moves with the fill handle.

Symptom: The first row is right, then the formula drifts as it is copied down or across.

First fix: Lock the fixed part with $, then fill down and compare three rows against a manual calculation.

The pivot cache is stale, the value field uses COUNT instead of SUM, the chart range excludes new rows, or the visual compares different time periods.

Symptom: The chart looks polished but sums the wrong column, counts instead of sums, or hides a category.

First fix: Refresh the pivot, confirm the aggregation and source range, then read the chart back against the raw total.

A sheet was renamed or deleted, an external workbook moved, or the submitted filename no longer matches the one referenced by the grader.

Symptom: The workbook worked yesterday, but now shows #REF! or cannot find a linked file.

First fix: Update the references, remove external links, and submit with the exact filename and sheet names in the brief.