tui-cs/Terminal.Gui · error · JsonException

After {propertyName}: Expected a JSON property name, but got

Error message

After {propertyName}: Expected a JSON property name, but got "{reader.TokenType}"

What it means

Inside a scope object (SettingsScope/ThemeScope), after reading a property value, the next token is not a PropertyName — malformed JSON such as a missing comma, a stray value, or wrong nesting. Mirrors the Scheme-level error 67 but at the Scope level.

Source

Thrown at Terminal.Gui/Configuration/ScopeJsonConverter.cs:50

    {
        if (reader.TokenType != JsonTokenType.StartObject)
        {
            throw new JsonException ($$"""Expected a JSON object ("{ "propName" : ... }"), but got "{{reader.TokenType}}".""");
        }

        var scope = (TScopeT)Activator.CreateInstance (typeof (TScopeT))!;
        var propertyName = string.Empty;

        while (reader.Read ())
        {
            if (reader.TokenType == JsonTokenType.EndObject)
            {
                return scope!;
            }

            if (reader.TokenType != JsonTokenType.PropertyName)
            {
                throw new JsonException ($"After {propertyName}: Expected a JSON property name, but got \"{reader.TokenType}\"");
            }

            propertyName = reader.GetString ();
            reader.Read ();

            // Get the hardcoded property from the TscopeT (e.g. ThemeScope.GetHardCodedProperty)
            ConfigProperty? configProperty = scope.GetHardCodedProperty (propertyName!);

            if (propertyName is { } && configProperty is { })
            {
                // This property name was found in the cached hard-coded scope dict.

                // Add it, with no value
                configProperty.HasValue = false;
                configProperty.PropertyValue = null;
                scope.TryAdd (propertyName, configProperty);

                // Figure out if it needs a JsonConverter and if so, create one

View on GitHub (pinned to 2e47b11478)

Solutions

1. Run the config through a JSON linter.
2. Fix missing commas / nesting; ensure flat key:value pairs separated by commas.

Example fix

// before
{ "Schemes": {...} "Themes": {...} }
// after
{ "Schemes": {...}, "Themes": {...} }

// Pre-validate JSON syntax
try { JsonDocument.Parse (File.ReadAllText (path)); }
catch (JsonException ex) { /* missing comma / bad nesting; ex has position */ }

try { ConfigurationManager.Apply (); }
catch (JsonException ex) when (ex.Message.Contains ("Expected a JSON property name"))
{ /* ex.Message names the last propertyName before the error */ }

When it happens

Trigger: A scope object with missing commas, stray tokens, or mis-nested values, e.g. { "Schemes": {...} "Themes": {...} }.

Common situations: Hand-editing config and dropping commas; a templating tool emitting malformed JSON.

Related errors

• Expected a JSON object ("{ "propName" : ... }"), but got "{r
• After {propertyName}: Expected PropertyName but got another
• After {propertyName}: Invalid Json.
• {propertyName}: Unknown property name.
• Unexpected StartObject token when parsing Attribute: {reader

AI-assisted analysis of tui-cs/Terminal.Gui@2e47b11478 (2026-08-13). Data as JSON: /api/errors/2246a2f69c861d56. Report an issue: GitHub.