spectreconsole/spectre.console · error · InvalidOperationException

Invalid Figlet font header

Error message

Invalid Figlet font header

What it means

Thrown by ParseHeader after splitting the header line into whitespace-delimited tokens when fewer than 6 parts are present. A valid FIGlet header has at least 6 fields (signature+hardblank, height, baseline, max length, old layout, comment lines). Too few tokens means the header is truncated.

Source

Thrown at src/Spectre.Console/Widgets/Figlet/FigletFontParser.cs:107

        {
            index = index.ReplaceExact("0x", string.Empty);
            style = NumberStyles.HexNumber;
        }

        return int.TryParse(index, style, CultureInfo.InvariantCulture, out result);
    }

    private static FigletHeader ParseHeader(string text)
    {
        if (string.IsNullOrWhiteSpace(text))
        {
            throw new InvalidOperationException("Invalid Figlet font");
        }

        var parts = text.SplitWords(StringSplitOptions.RemoveEmptyEntries);
        if (parts.Length < 6)
        {
            throw new InvalidOperationException("Invalid Figlet font header");
        }

        if (!IsValidSignature(parts[0]))
        {
            throw new InvalidOperationException("Invalid Figlet font header signature");
        }

        int? fullLayout = null;
        if (parts.Length > 7 && int.TryParse(parts[7], NumberStyles.Integer, CultureInfo.InvariantCulture, out var fl))
        {
            fullLayout = fl;
        }

        return new FigletHeader
        {
            Hardblank = parts[0][5],
            Height = int.Parse(parts[1], CultureInfo.InvariantCulture),
            Baseline = int.Parse(parts[2], CultureInfo.InvariantCulture),

View on GitHub (pinned to 0acc92fada)

Solutions

1. Open the font file and verify the header line has at least 6 space-separated fields.
2. Use a FIGlet font from the standard distribution known to parse correctly.
3. Regenerate or re-download the font file if it is truncated.

Example fix

// before (header has too few fields)
// flf2a$ 5

// after (complete header)
// flf2a$ 5 4 16 15 11 0 24463

var parts = headerLine.SplitWords(StringSplitOptions.RemoveEmptyEntries);
if (parts.Length < 6) throw new ArgumentException("Figlet header must have >= 6 fields");

static bool HasEnoughHeaderFields(string headerLine) => headerLine.SplitWords(StringSplitOptions.RemoveEmptyEntries).Length >= 6;

When it happens

Trigger: Passing a FIGlet font whose header line is incomplete or where fields are joined together preventing proper SplitWords tokenization.

Common situations: Manual editing of a font header that deleted fields, a font in a non-standard variant, or whitespace normalization that merged fields.

Related errors

• Invalid Figlet font
• Could not read header line
• Invalid Figlet font header signature
• Invalid JSON
• Encountered closing tag when none was expected near position

AI-assisted analysis of spectreconsole/spectre.console@0acc92fada (2026-08-13). Data as JSON: /api/errors/3c80971e755e204c. Report an issue: GitHub.