spectreconsole/spectre.console · error · InvalidOperationException

Invalid RGB color '{rgb}'. {ex.Message}

Error message

Invalid RGB color '{rgb}'. {ex.Message}

What it means

ParseRgbColor caught an exception converting the component strings to bytes (e.g. non-numeric, out-of-byte-range overflow). The inner exception message is appended, e.g. for `[rgb(255,a,0)]` or `[rgb(300,0,0)]`.

Source

Thrown at src/Spectre.Console.Ansi/AnsiMarkupTagParser.cs:10

namespace Spectre.Console;

internal static class AnsiMarkupTagParser
{
    public static (Style Style, Link? Link) Parse(string text)
    {
        var result = Parse(text, out var error);
        if (error != null)
        {
            throw new InvalidOperationException(error);
        }

        return result ?? throw new InvalidOperationException("Could not parse style.");
    }

    public static bool TryParse(string text, [NotNullWhen(true)] out (Style Style, Link?)? result)
    {
        result = Parse(text, out _);
        return result != null;
    }

    private static (Style Style, Link? Link)? Parse(string text, out string? error)
    {
        var effectiveDecoration = (Decoration?)null;
        var effectiveForeground = (Color?)null;
        var effectiveBackground = (Color?)null;
        var effectiveLink = (string?)null;

View on GitHub (pinned to 0acc92fada)

Solutions

1. Use three integer components each in 0-255, e.g. rgb(255,128,0)
2. Clamp and round floats: (byte)Math.Round(Math.Clamp(v,0,255))
3. Validate with a regex like ^rgb\((\d{1,3}),(\d{1,3}),(\d{1,3})\)$

Example fix

// before
AnsiMarkup.Parse("[rgb(255,a,0)]text[/]");

// after
AnsiMarkup.Parse("[rgb(255,160,0)]text[/]");

public static bool IsValidRgb(string token)
{
    var m = Regex.Match(token, @"^rgb\((\d{1,3}),(\d{1,3}),(\d{1,3})\)$");
    return m.Success && m.Groups.Cast<Group>().Skip(1).All(g => int.Parse(g.Value) is >= 0 and <= 255);
}

try { AnsiMarkup.Parse(markup); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Invalid RGB color"))
{ /* clamp components to 0-255 and rebuild as rgb(r,g,b) */ }

When it happens

Trigger: An `rgb(...)` part whose components aren't parseable bytes: non-numeric characters, or values outside 0-255 that overflow Convert.ToInt32→byte cast.

Common situations: Feeding floating-point or percentage values like `rgb(50%,50%,50%)`; values >255 from unclamped math; localized decimal separators.

Related errors

• Invalid RGB color '{rgb}'.
• Color number must be greater than or equal to 0 (was {number
• Color number must be less than or equal to 255 (was {number}
• Could not find color '{part}'.
• Could not find color or style '{part}'.

AI-assisted analysis of spectreconsole/spectre.console@0acc92fada (2026-08-13). Data as JSON: /api/errors/003efc6d16f19933. Report an issue: GitHub.