iOfficeAI/OfficeCLI · error · ArgumentException

Invalid majorUnit '{value}': must be a positive number (OOXM

Error message

Invalid majorUnit '{value}': must be a positive number (OOXML ST_AxisUnit > 0).

What it means

Thrown when 'majorUnit' is not a positive number. OOXML ST_AxisUnit requires a double > 0; a value of 0 or negative makes Excel refuse to draw ticks (or freeze the chart in older builds). SafeParseDouble handles the non-numeric case separately; this throw fires only for a successfully parsed but non-positive number.

Source

Thrown at src/officecli/Core/Chart/ChartHelper.Setter.cs:1044

                    // Schema order: logBase?, orientation, max?, min? — insert max after orientation
                    var orient = scaling.GetFirstChild<C.Orientation>();
                    if (orient != null) orient.InsertAfterSelf(maxEl);
                    else scaling.PrependChild(maxEl);
                    break;
                }

                case "majorunit":
                {
                    var plotArea2 = chart.GetFirstChild<C.PlotArea>();
                    var valAxis = plotArea2?.GetFirstChild<C.ValueAxis>();
                    if (valAxis == null) { unsupported.Add(key); break; }
                    var mu = ParseHelpers.SafeParseDouble(value, "majorunit");
                    // OOXML ST_AxisUnit: positive double. 0 or negative would
                    // make Excel refuse to draw any tick on the axis (or, in
                    // older builds, freeze the chart). Reject up front instead
                    // of writing garbage that opens to a blank plot area.
                    if (!(mu > 0))
                        throw new ArgumentException($"Invalid majorUnit '{value}': must be a positive number (OOXML ST_AxisUnit > 0).");
                    valAxis.RemoveAllChildren<C.MajorUnit>();
                    InsertValAxChildInOrder(valAxis, new C.MajorUnit { Val = mu });
                    break;
                }

                case "minorunit":
                {
                    var plotArea2 = chart.GetFirstChild<C.PlotArea>();
                    var valAxis = plotArea2?.GetFirstChild<C.ValueAxis>();
                    if (valAxis == null) { unsupported.Add(key); break; }
                    var nu = ParseHelpers.SafeParseDouble(value, "minorunit");
                    if (!(nu > 0))
                        throw new ArgumentException($"Invalid minorUnit '{value}': must be a positive number (OOXML ST_AxisUnit > 0).");
                    valAxis.RemoveAllChildren<C.MinorUnit>();
                    InsertValAxChildInOrder(valAxis, new C.MinorUnit { Val = nu });
                    break;
                }

View on GitHub (pinned to 1ced45e900)

Solutions

1. Pass a strictly positive majorUnit (e.g. 10, 0.5).
2. If you want Excel to auto-compute the interval, omit majorUnit instead of sending 0.
3. Compute the interval from the data range and guard against zero before calling Set.

Example fix

// before
SetChartProperties(part, new() { ["majorUnit"] = "0" });
// after
if (interval > 0)
    SetChartProperties(part, new() { ["majorUnit"] = interval.ToString(CultureInfo.InvariantCulture) });

static bool IsValidAxisUnit(string v, out double unit) =>
    double.TryParse(v, NumberStyles.Float, CultureInfo.InvariantCulture, out unit)
    && unit > 0;

static bool IsPositiveUnit(double v) => v > 0 && !double.IsInfinity(v);

try { SetChartProperties(part, props); }
catch (ArgumentException ex) when (ex.Message.StartsWith("Invalid majorUnit"))
{ /* omit majorUnit to let Excel auto-compute, or recompute from data */ }

When it happens

Trigger: SetChartProperties with { ["majorUnit"] = "0" }, "-5", or a parsed value that collapses to <= 0.

Common situations: Auto-generated tick interval of 0 from a data pipeline; sign error computing interval from data range; replaying a dump where the source chart had no majorUnit (empty) mis-encoded as 0.

Related errors

• axisMin={value} is invalid on a log-scaled axis: a logarithm
• Invalid minorUnit '{value}': must be a positive number (OOXM
• Invalid 'tickLabelPos' value: '{value}'. Valid: none, high,
• Invalid 'axisPos' value: '{value}'. Valid: top, bottom, left
• Invalid 'crosses' value: '{value}'. Valid: autoZero, max, mi

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/23244594c02e62e5. Report an issue: GitHub.