spectreconsole/spectre.console · error · InvalidOperationException

Could not find color '{part}'.

Error message

Could not find color '{part}'.

What it means

After the `on` keyword, foreground is false so the part is expected to be a background color. When the part matches no known color name, is not a valid hex/rgb/integer, the parser reports 'Could not find color {part}.' This string is re-thrown by the public Parse.

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 a color name present in ColorTable (standard names like red, blue, green, etc.)
2. Use `#rrggbb`, `rgb(r,g,b)`, or a 0-255 index for the background
3. Use `default` to leave the background unset
4. Double-check spelling and that the token comes after `on`

Example fix

// before
AnsiMarkup.Parse("[red on purpel]text[/]");

// after
AnsiMarkup.Parse("[red on purple]text[/]");

// Validate a background token against known forms before embedding:
public static bool IsValidBgToken(string token) =>
    ColorTable.GetColor(token) != null
    || Regex.IsMatch(token, @"^#[0-9A-Fa-f]{6}$")
    || Regex.IsMatch(token, @"^rgb\(\d{1,3},\d{1,3},\d{1,3}\)$")
    || token == "default";

try { AnsiMarkup.Parse(markup); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Could not find color"))
{ /* replace unknown bg token with 'default' or a known name */ }

When it happens

Trigger: A background position holding an unrecognized token, e.g. `[red on purpel]` (typo), `[on notacolor]`, or `[on default default]` where the second 'default' after `on` is not a recognized color.

Common situations: Misspelled color name; using a decoration keyword (e.g. `bold`) in the background slot; expecting a custom color name that isn't registered.

Related errors

• 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 or style '{part}'.
• A foreground color has already been set.
• A background color has already been set.

AI-assisted analysis of spectreconsole/spectre.console@0acc92fada (2026-08-13). Data as JSON: /api/errors/7562ffc06dbbc7eb. Report an issue: GitHub.