iOfficeAI/OfficeCLI · error · ArgumentException

Invalid referenceLine width '{widthStr}'. Expected a number

Error message

Invalid referenceLine width '{widthStr}'. Expected a number in points (e.g. '1.5'), or empty for default {DefaultWidthPt}pt.

What it means

In the canonical 5-part referenceLine form (value:color:width:dash:label), parts[2] is the line width in points. If the width segment is non-empty and fails double.TryParse (InvariantCulture), the library rejects it. An empty width segment is valid and defaults to DefaultWidthPt. This only applies to the 5-part form; the 3-part form treats parts[2] as a label.

Source

Thrown at src/officecli/Core/Chart/ChartHelper.Advanced.cs:87

                widthPt = w4;
                dash = p3;
            }
            else
            {
                label = p2;
                dash = p3;
            }
        }
        else if (parts.Length >= 5)
        {
            // Canonical 5-part form: value:color:width:dash:label (extra parts after label are joined
            // back with ':' so labels containing literal colons survive a round-trip).
            var widthStr = parts[2].Trim();
            if (widthStr.Length > 0)
            {
                if (!double.TryParse(widthStr, System.Globalization.NumberStyles.Float,
                        System.Globalization.CultureInfo.InvariantCulture, out widthPt))
                    throw new ArgumentException(
                        $"Invalid referenceLine width '{widthStr}'. Expected a number in points (e.g. '1.5'), or empty for default {DefaultWidthPt}pt.");
            }
            dash = parts[3].Trim();
            label = string.Join(':', parts.Skip(4)).Trim();
        }

        if (widthPt <= 0 || widthPt > 100)
            throw new ArgumentException(
                $"Invalid referenceLine width '{widthPt.ToString("G", System.Globalization.CultureInfo.InvariantCulture)}'. Expected a positive number of points, typically 0.25–10.");

        // Warn: percent-stacked value axis is 0-1 (displayed 0%-100%). A refValue > 1
        // is almost always a mistake — user likely forgot to convert 50 → 0.5.
        // Without this check, Excel silently stretches the val axis to fit (e.g. 5000%),
        // producing a chart where the real bars are compressed to a thin sliver on the left.
        if (refValue > 1.0 && IsPercentStackedChart(plotArea))
        {
            var refMsg =
                $"referenceLine value {refValue.ToString("G", System.Globalization.CultureInfo.InvariantCulture)} "

View on GitHub (pinned to 1ced45e900)

Solutions

  1. Ensure the width segment (parts[2] in the 5-part form) is a numeric value in points: '50:FF0000:1.5:dash:Label'.
  2. Leave the width segment empty to use the default: '50:FF0000::dash:Label'.
  3. If you intended a 3-part form with a label, remember that parts[2] in a 3-part spec is the label, not the width — add width only in the 5-part form.

Example fix

// before
referenceline: "50:FF0000:thick:dash:Target"
// after
referenceline: "50:FF0000:1.5:dash:Target"
// or empty width for default
referenceline: "50:FF0000::dash:Target"
Defensive patterns

Strategy: validation

Validate before calling

static bool TryValidateRefLineWidth(string spec)
{
    var parts = spec.Split(':');
    if (parts.Length < 5) return true; // 5-part form only
    var widthStr = parts[2].Trim();
    if (widthStr.Length == 0) return true; // empty = default
    return double.TryParse(widthStr, System.Globalization.NumberStyles.Float,
        System.Globalization.CultureInfo.InvariantCulture, out _);
}

Try / catch

try { ChartHelperAdvanced.AddReferenceLine(chart, spec); }
catch (ArgumentException ex) when (ex.Message.Contains("Invalid referenceLine width") && ex.Message.Contains("Expected a number"))
{
    Console.Error.WriteLine($"Width segment is non-numeric. Use a number or leave empty for default.");
}

Prevention

When it happens

Trigger: Passing a referenceLine spec with 5+ colon-separated segments where the third segment (width) is non-numeric: '50:FF0000:thick:dash:Label'. The spec must have >= 5 parts to enter this code path.

Common situations: Confusing the 3-part form (value:color:label) with the 5-part form (value:color:width:dash:label) and placing a non-numeric string in the width slot. Using locale-specific decimal separators in the width ('1,5' instead of '1.5').

Related errors

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/7c5bca3540980a0d. Report an issue: GitHub.