tui-cs/Terminal.Gui · error · InvalidOperationException

Current Theme does not have a Scheme.

Error message

Current Theme does not have a Scheme.

What it means

GetSchemesForCurrentTheme reads the active theme's "Schemes" config property and expects a Dictionary<string,Scheme?>. If the property value is null or not that dictionary type — typically because the "Schemes" key was omitted from the theme config — this InvalidOperationException is thrown.

Source

Thrown at Terminal.Gui/Configuration/SchemeManager.cs:222

    }

    /// <summary>
    ///     Get the dictionary of schemes from the current theme. Current means active.
    /// </summary>
    /// <returns></returns>
    public static Dictionary<string, Scheme?> GetSchemesForCurrentTheme ()
    {
        lock (_schemesLock)
        {
            if (!ConfigurationManager.IsInitialized ())
            {
                throw new InvalidOperationException ("CM Must be Initialized");
            }

            if (ThemeManager.GetCurrentTheme () ["Schemes"].PropertyValue is not Dictionary<string, Scheme?> schemes)
            {
                // Most likely because "Schemes": was left out of the config
                throw new InvalidOperationException ("Current Theme does not have a Scheme.");
            }

            return schemes;
        }
    }

    /// <summary>
    ///     Convenience method to get the names of the schemes.
    /// </summary>
    /// <returns></returns>
    public static ImmutableList<string> GetSchemeNames ()
    {
        lock (_schemesLock)
        {
            return GetSchemes ().Keys.ToImmutableList ();
        }
    }

View on GitHub (pinned to 2e47b11478)

Solutions

1. Ensure the theme JSON includes a "Schemes" object (copy the Schemes block from the default theme).
2. Load a complete theme via ThemeManager, or add schemes via AddScheme.
3. Use TryGetScheme (which returns false instead of throwing) when absence is expected.

Example fix

// before
{ "Theme": { "Name": "MyTheme" } }
// after
{ "Theme": { "Name": "MyTheme", "Schemes": { "Base": { "Normal": { "Foreground": "White" } } } } }

bool themesHasSchemes =
    ThemeManager.GetCurrentTheme () ["Schemes"].PropertyValue
    is Dictionary<string, Scheme?>;

try { var schemes = SchemeManager.GetSchemesForCurrentTheme (); }
catch (InvalidOperationException ex) when (ex.Message.Contains ("does not have a Scheme"))
{ /* theme omitted the Schemes block; fall back to AddScheme or load a full theme */ }

When it happens

Trigger: A theme config JSON that defines settings but omits the "Schemes" object entirely; a partially-applied theme; calling GetSchemesForCurrentTheme before the theme's Schemes were populated.

Common situations: Custom theme missing the Schemes section; upgrading without including the required Schemes block; ConfigurationManager.Apply on a config lacking Schemes.

Related errors

• Unexpected StartObject token when parsing Scheme: {reader.To
• After {propertyName}: Expected Attribute but got {attrObj?.G
• {propertyName}: Unrecognized Scheme Attribute name.
• {schemeName}: Cannot remove a built-in Scheme.
• {schemeName}: Does not exist in Schemes.

AI-assisted analysis of tui-cs/Terminal.Gui@2e47b11478 (2026-08-13). Data as JSON: /api/errors/870ce6b0d5f64aea. Report an issue: GitHub.