CoplayDev/unity-mcp · error · JsonException

Failed to parse float at index {i}: '{arr[i]}'

Error message

Failed to parse float at index {i}: '{arr[i]}'

What it means

ParseFloatArray iterates a JArray and calls ToObject<float> on each element. When an element cannot be converted to float, the exception is rethrown with the failing index and the raw token value for diagnosis.

Source

Thrown at MCPForUnity/Editor/Tools/ManageScene.cs:84

            public bool? autoRepair { get; set; }        // for validate with auto-repair
        }

        private static float[] ParseFloatArray(JToken token)
        {
            if (token == null || token.Type == JTokenType.Null) return null;
            if (token.Type == JTokenType.Array)
            {
                var arr = (JArray)token;
                var result = new float[arr.Count];
                for (int i = 0; i < arr.Count; i++)
                {
                    try
                    {
                        result[i] = arr[i].ToObject<float>();
                    }
                    catch (Exception ex)
                    {
                        throw new Newtonsoft.Json.JsonException(
                            $"Failed to parse float at index {i}: '{arr[i]}'", ex);
                    }
                }
                return result;
            }
            // Single value → array of one
            var single = ParamCoercion.CoerceFloatNullable(token);
            return single.HasValue ? new[] { single.Value } : null;
        }

        private static SceneCommand ToSceneCommand(JObject p)
        {
            if (p == null) return new SceneCommand();
            var toolParams = new ToolParams(p);
            return new SceneCommand
            {
                action = (p["action"]?.ToString() ?? string.Empty).Trim().ToLowerInvariant(),
                name = p["name"]?.ToString() ?? string.Empty,

View on GitHub (pinned to c21bf496bc)

Solutions

1. Ensure every element of the array is a numeric value.
2. Validate the array contents before sending the command.
3. If sending a single value, pass it directly (the function coerces a single value to a one-element array).

Example fix

// before
{ "orbit_elevations": ["low", 30, 60] }
// after
{ "orbit_elevations": [10, 30, 60] }

if (token.Type == JTokenType.Array)
{
    for (int i = 0; i < token.Count(); i++)
        if (token[i].Type != JTokenType.Float && token[i].Type != JTokenType.Integer)
            throw new ArgumentException($"Array element {i} is not numeric: '{token[i]}'");
}

static bool IsNumericArray(JToken t)
{
    if (t == null || t.Type == JTokenType.Null) return true;
    if (t.Type == JTokenType.Float || t.Type == JTokenType.Integer) return true;
    if (t.Type != JTokenType.Array) return false;
    foreach (var e in t)
        if (e.Type != JTokenType.Float && e.Type != JTokenType.Integer) return false;
    return true;
}

When it happens

Trigger: A float-array parameter (e.g. orbit_elevations, position/rotation arrays) contains a non-numeric value: a string like 'high', null, a boolean, or a nested object/array.

Common situations: An LLM sends strings instead of numbers; a payload mixes types; a caller reuses a value meant for another field.

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

• Color array must have 3 or 4 elements.
• Failed to parse 'properties' JSON string. Raw value: {token}
• Failed to parse 'properties' JSON string. Raw value: {token}
• set-pixels must be a JSON object
• import_settings must be a JSON object

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/7a8219ece4b64496. Report an issue: GitHub.