tui-cs/Terminal.Gui · error · JsonException

Unexpected token type in TraceCategory array: {reader.TokenT

Error message

Unexpected token type in TraceCategory array: {reader.TokenType}

What it means

Thrown by TraceCategoryJsonConverter.Read while parsing the array form of a TraceCategory value: an element inside the JSON array is not a string token. The array form (["Command","Mouse"]) requires every element to be a JsonTokenType.String; numbers, booleans, null, or nested arrays/objects are rejected per-element.

Source

Thrown at Terminal.Gui/Configuration/TraceCategoryJsonConverter.cs:47

            throw new JsonException ($"Invalid TraceCategory value: '{value}'");
        }

        if (reader.TokenType == JsonTokenType.StartArray)
        {
            // Handle array format: ["Command", "Mouse"]
            var result = TraceCategory.None;

            while (reader.Read ())
            {
                if (reader.TokenType == JsonTokenType.EndArray)
                {
                    break;
                }

                if (reader.TokenType != JsonTokenType.String)
                {
                    throw new JsonException ($"Unexpected token type in TraceCategory array: {reader.TokenType}");
                }
                string value = reader.GetString ()!;

                if (Enum.TryParse (value, true, out TraceCategory category))
                {
                    result |= category;
                }
                else
                {
                    throw new JsonException ($"Invalid TraceCategory value in array: '{value}'");
                }
            }

            return result;
        }

        throw new JsonException ($"Unexpected token type for TraceCategory: {reader.TokenType}");
    }

View on GitHub (pinned to 2e47b11478)

Solutions

1. Make every element of the TraceCategory array a string literal that names a TraceCategory member.
2. If you want a numeric, switch the whole value to the scalar integer form (e.g. 6) instead of an array.
3. Validate the array with a JSON schema or jq to confirm all elements are strings.

Example fix

// before
"TraceCategory": ["Command", 2]
// after
"TraceCategory": ["Command", "Mouse"]
// or scalar
"TraceCategory": 6

// Validate a TraceCategory array contains only strings
bool IsStringOnlyArray (JsonElement el)
    => el.ValueKind == JsonValueKind.Array && el.EnumerateArray ().All (e => e.ValueKind == JsonValueKind.String);

static bool IsTraceCategoryArrayValid (JsonElement el)
    => el.ValueKind == JsonValueKind.Array && el.EnumerateArray ().All (e => e.ValueKind == JsonValueKind.String && Enum.TryParse<TraceCategory> (e.GetString (), true, out _));

ConfigurationManager.ThrowOnJsonErrors = false;

When it happens

Trigger: Writing a TraceCategory array with mixed content such as ["Command", 2] or ["Mouse", true], or accidentally nesting [["Command"]].

Common situations: Mixing the integer and string forms inside one array; a JSON generator emitting numbers where strings were expected; copy-paste errors.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Invalid TraceCategory value: '{value}'
• Invalid TraceCategory value in array: '{value}'
• Unexpected token type for TraceCategory: {reader.TokenType}
• Unexpected StartObject token when parsing Attribute: {reader
• {propertyName}: Both Foreground and Background colors must b

AI-assisted analysis of tui-cs/Terminal.Gui@2e47b11478 (2026-08-13). Data as JSON: /api/errors/1230def32ad82f85. Report an issue: GitHub.