XINCGer/Unity3DTraining · error · InvalidProtocolBufferException

Invalid numeric value:

Error message

Invalid numeric value: 

What it means

ParseNumericString validates textual numeric tokens before delegating to int/long/double parsers. The protobuf JSON spec forbids a leading '+' on numbers, so any text starting with '+' is rejected with InvalidProtocolBufferException. JSON numbers must follow the strict JSON grammar; '+5' is invalid JSON.

Solutions

1. Remove the leading '+' from the numeric string (an unsigned positive number needs no sign)
2. Fix the formatter producing the string (e.g. drop the '+' section in a .NET format string)
3. Parse with double/int.Parse on the cleaned value before embedding it into JSON
4. Pre-strip or reject '+'-prefixed numerics in your JSON preprocessing step

Example fix

// before
string json = "{\"score\": \"+10\"}"; // leading '+' rejected
// after
string json = "{\"score\": 10}";

static readonly System.Text.RegularExpressions.Regex JsonNumber =
    new System.Text.RegularExpressions.Regex(@"^-?(0|[1-9]\d*)(\.\d+)?([eE][+-]?\d+)?$");
bool IsValidJsonNumber(string text) => JsonNumber.IsMatch(text);

try { return JsonParser.Default.Parse<T>(json); }
catch (InvalidProtocolBufferException ex) when (ex.Message.StartsWith("Invalid numeric value")) {
    logger.LogWarning(ex, "Malformed JSON number");
    return null;
}

When it happens

Trigger: Calling JsonParser.Parse<T> with numeric fields whose values are written with an explicit plus sign, e.g. {"score": "+10"} where a string-form numeric is parsed, or code that formats numbers with a custom format string including a sign specifier ('+0;-0;0').

Common situations: Config files hand-edited with '+value' notation; log/telemetry strings that carry explicit signs; sprintf-style formatting with '+' flag reused to build JSON; pasting values from spreadsheets.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• Invalid numeric value for type:
• Value out of range
• Invalid field type
• Unable to format value of type
• Type registry has no descriptor for type name '

AI-assisted analysis of XINCGer/Unity3DTraining@016f98412e (2026-09-12). Data as JSON: /api/errors/4ed8a67426dc7a9c. Report an issue: GitHub.

Appendix: source

Thrown at NetWorkAndResources/Socket_Protobuff/Assets/Plugins/Google.Protobuf/JsonParser.cs:738

                default:
                    throw new InvalidProtocolBufferException("Unsupported conversion from JSON string for field type " + field.FieldType);
            }
        }

        /// <summary>
        /// Creates a new instance of the message type for the given field.
        /// </summary>
        private static IMessage NewMessageForField(FieldDescriptor field)
        {
            return field.MessageType.Parser.CreateTemplate();
        }

        private static T ParseNumericString<T>(string text, Func<string, NumberStyles, IFormatProvider, T> parser)
        {
            // Can't prohibit this with NumberStyles.
            if (text.StartsWith("+"))
            {
                throw new InvalidProtocolBufferException("Invalid numeric value: " + text);
            }
            if (text.StartsWith("0") && text.Length > 1)
            {
                if (text[1] >= '0' && text[1] <= '9')
                {
                    throw new InvalidProtocolBufferException("Invalid numeric value: " + text);
                }
            }
            else if (text.StartsWith("-0") && text.Length > 2)
            {
                if (text[2] >= '0' && text[2] <= '9')
                {
                    throw new InvalidProtocolBufferException("Invalid numeric value: " + text);
                }
            }
            try
            {
                return parser(text, NumberStyles.AllowLeadingSign | NumberStyles.AllowDecimalPoint | NumberStyles.AllowExponent, CultureInfo.InvariantCulture);

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