Release note · August 1, 2026
The spreadsheet formula risk that appears only after a source workbook closes
A spreadsheet can look healthy in review and still fail in the next operational handoff: a linked source workbook closes. Microsoft documents this limitation for COUNTIF and COUNTIFS, and its SUMIF/SUMIFS guidance identifies the same closed-workbook behavior for the related function family.
FormulaFence 0.216.0 adds FF114, a medium-severity, workbook-level safeguard for direct external A1 references in native COUNTBLANK, COUNTIF, COUNTIFS, SUMIF, and SUMIFS calls. It reports a dependency to review, not a claim that a current workbook is failing: FormulaFence does not resolve the link, inspect whether the source is open, or evaluate a formula.
Why one workbook finding matters
Copied conditional formulas can occur at extraordinary scale. A per-cell alert would turn a useful operational signal into report noise, so FF114 produces one bounded finding per workbook. Its JSON, Markdown, and SARIF evidence keeps only aggregate function, formula-cell, and external-reference-argument counts. Source paths, workbook names, sheet names, addresses, formulas, and values never enter the evidence.
The rule is intentionally strict: only exact native spellings (with optional @), complete nonempty arity, and directly visible external A1 tokens qualify. Text-built or computed references, external names, Tables, 3-D references, malformed or explicit #REF! syntax, array territory, and arbitrary namespaces stay quiet. A saved #VALUE! result remains separate FF109 evidence because the syntax alone cannot establish why Excel produced it.
Evidence without pretending to know the source state
An aggregate-only SpreadsheetBench v0.1 census covered 5,464 public workbook artifacts and 1,200,528 ordinary formula instances. It found 444,523 complete calls in this narrow external-reference boundary across 2,206,648 argument spans; 15,949 corresponding formula instances had a saved #VALUE! result. That is prevalence and last-saved-state context, not proof that any source workbook was closed or that the external dependency caused the error.
The release passed 1,542 tests, hosted CI, package lint and compilation, fresh wheel and source-distribution installs, and a downloaded public-release-wheel install. The full validation record explains the boundary and the aggregate methodology.
FormulaFence is available under MIT on GitHub. For the broader spreadsheet CI approach, see Spreadsheet changes that can pass CI.