What causes "Tried to read non-float json value as float" in Unity-Technologies/UnityCsReference?

Check IsFloat() (or read via AsFloat(true) which yields 0.0f) before committing to the typed read.

Unity-Technologies/UnityCsReference · error · JSONTypeException

Tried to read non-float json value as float

Error message

Tried to read non-float json value as float

What it means

JSONValue.AsFloat(bool nothrow) returns the wrapped value only when it is a float; otherwise (with nothrow false, used by the parameterless AsFloat()) it throws JSONTypeException. Because the library stores numbers specifically as float, an integer-looking JSON number that was parsed as float will work, but a string or bool will not, and there is no implicit parsing of numeric strings.

Source

Thrown at Editor/Mono/AssetStore/Json.cs:93

        {
            if (data is string)
                return (string)data;
            if (!nothrow)
                throw new JSONTypeException("Tried to read non-string json value as string");
            return "";
        }

        public string AsString()
        {
            return AsString(false);
        }

        public float AsFloat(bool nothrow)
        {
            if (data is float)
                return (float)data;
            if (!nothrow)
                throw new JSONTypeException("Tried to read non-float json value as float");
            return 0.0f;
        }

        public float AsFloat()
        {
            return AsFloat(false);
        }

        public bool AsBool(bool nothrow)
        {
            if (data is bool)
                return (bool)data;
            if (!nothrow)
                throw new JSONTypeException("Tried to read non-bool json value as bool");
            return false;
        }

        public bool AsBool()

View on GitHub (pinned to 225b0fbdb5)

Solutions

Check IsFloat() (or read via AsFloat(true) which yields 0.0f) before committing to the typed read.
If the source is a numeric string, call AsString(true) then float.TryParse it.
Normalize/validate the response shape before consumption.

Example fix

// before
float v = node["price"].AsFloat(); // throws if "price" is "9.99"

// after
float v;
if (node["price"].IsString())
    float.TryParse(node["price"].AsString(),
        System.Globalization.NumberStyles.Float,
        System.Globalization.CultureInfo.InvariantCulture, out v);
else
    v = node["price"].AsFloat(true);

Defensive patterns

Strategy: type-guard

Validate before calling

float ReadFloat(JSONValue v) {
    if (v.IsFloat()) return v.AsFloat();
    if (v.IsString() && float.TryParse(v.AsString(), System.Globalization.NumberStyles.Float, System.Globalization.CultureInfo.InvariantCulture, out var f)) return f;
    return 0f;
}

Type guard

static float AsFloatOr(JSONValue v, float fallback) => v.IsFloat() ? v.AsFloat() : fallback;

Try / catch

float f;
try { f = v.AsFloat(); } catch (JSONTypeException) { f = 0f; }

Prevention

Prefer IsFloat() / AsFloat(true) for numeric fields with mixed encodings.
Parse numeric strings explicitly with InvariantCulture to avoid locale bugs.
Log field types during development to detect schema changes.

When it happens

Trigger: Calling AsFloat() on a value that is a string (e.g. "1.5"), bool, object, or array; reading a numeric field that the server sent as a quoted string.

Common situations: API returns numbers as strings; mixed-schema responses; field repurposed from number to string across versions.

Related errors

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/e5a9796e5380887a. Report an issue: GitHub.