iOfficeAI/OfficeCLI · error · ArgumentException

Invalid color value: '{value}'. Expected 6-digit hex RGB (e.

Error message

Invalid color value: '{value}'. Expected 6-digit hex RGB (e.g. FF0000), 8-digit AARRGGBB (e.g. 80FF0000), 3-digit shorthand (e.g. F00) or 4-digit #RGBA shorthand (e.g. F00A), named color (e.g. red), rgb()/rgba()/hsl()/hsla() notation, or 'transparent'.

What it means

Thrown by ParseHelpers.NormalizeArgbColor as the final fallthrough when the input matches none of the accepted color forms. The function returns an 8-char AARRGGBB string and accepts: named colors, rgb()/rgba()/hsl()/hsla(), 'transparent', 6-hex RGB, 8-hex AARRGGBB (or #RRGGBBAA), 3-hex shorthand, and #RGBA shorthand (non-zero alpha). Inner whitespace and any other shape are rejected.

Source

Thrown at src/officecli/Core/ParseHelpers.cs:602

            // (the explicit `transparent` keyword or 8-digit #00000000 form
            // exists for that intent and is unambiguous).
            hex = new string(new[]
            {
                hex[0], hex[0], hex[1], hex[1], hex[2], hex[2], hex[3], hex[3],
            });
        }
        if (hex.Length == 6 && hex.All(char.IsAsciiHexDigit))
            return "FF" + hex;
        if (hex.Length == 8 && hex.All(char.IsAsciiHexDigit))
        {
            // CONSISTENCY(color-input-form): #-prefixed 8-hex is CSS RRGGBBAA
            // (alpha last); bare 8-hex stays in OOXML AARRGGBB (alpha first).
            // Mirrors SanitizeColorForOoxml.
            if (hadHashPrefix)
                return hex.Substring(6, 2) + hex[..6];
            return hex;
        }
        throw new ArgumentException(
            $"Invalid color value: '{value}'. Expected 6-digit hex RGB (e.g. FF0000), " +
            $"8-digit AARRGGBB (e.g. 80FF0000), 3-digit shorthand (e.g. F00) or 4-digit #RGBA shorthand (e.g. F00A), " +
            $"named color (e.g. red), rgb()/rgba()/hsl()/hsla() notation, or 'transparent'.");
    }

    /// <summary>
    /// Word/PPT theme scheme color names (ECMA-376 §17.18.97 / §20.1.10.46).
    /// Keep lowercase — input is matched case-insensitively but the canonical
    /// OOXML serialization (and downstream readback) is lowercase.
    /// </summary>
    public static readonly HashSet<string> SchemeColorNames = new(StringComparer.OrdinalIgnoreCase)
    {
        "dark1", "light1", "dark2", "light2",
        "accent1", "accent2", "accent3", "accent4", "accent5", "accent6",
        "hyperlink", "followedHyperlink",
        // Extra variants seen in OOXML: text1/text2/background1/background2 alias dark/light.
        "text1", "text2", "background1", "background2",
        // BUG-R6-06: alternate Word theme color aliases (windowText / windowBackground)

View on GitHub (pinned to 1ced45e900)

Solutions

Use a supported literal form: 'FF0000', '#FF0000', 'F00', '80FF0000', '#FF0000AA', 'red', 'rgb(255,0,0)', 'transparent'.
For scheme/theme colors (accent1, dark2, hyperlink, …) use a property that accepts theme colors — NormalizeArgbColor does not resolve them.
Remove inner whitespace from the value (outer whitespace is auto-trimmed, inner is not).

Example fix

// before
fillColor="accent1"
// after
fillColor="FF0000"   // or use a theme-color-aware property for accent1

Defensive patterns

Strategy: validation

Validate before calling

// Cheap pre-check: normalize then confirm 8 hex digits came back, or it is a known literal form.
static bool IsAcceptableArgbColor(string value)
{
    try { return System.Text.RegularExpressions.Regex.IsMatch(
        OfficeCli.Core.ParseHelpers.NormalizeArgbColor(value), @"^[0-9A-F]{8}$"); }
    catch { return false; }
}

Try / catch

try { var argb = ParseHelpers.NormalizeArgbColor(value); }
catch (ArgumentException ex) { /* report invalid color to user, keep prior value */ }

Prevention

Use supported literal forms (hex, named, rgb(), transparent).
Route scheme/theme colors to theme-color-aware properties, not NormalizeArgbColor.
Avoid inner whitespace in color values.

When it happens

Trigger: Calling a property that routes through NormalizeArgbColor (Excel cell/rich-text-run/conditional-format/sparkline colors, ExcelStyleManager hex) with a value that is none of the accepted forms — e.g. 'accent1' (a scheme color, not handled here), a 5-digit hex, '#FF 0000' (inner space), 'rgb(300,0,0)' out of range, or a misspelled color name.

Common situations: Trying to set a theme/scheme color (accent1, dark2, hyperlink) on a property that only accepts literal colors — these must go on theme-color-aware properties; copying a CSS color with inner whitespace; typos in named colors ('redd'); truncated hex.

Related errors

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/34ce5372ef393dbb. Report an issue: GitHub.