json-path/JsonPath · error · JsonException

Unknown value type " + value.getValueType()

Error message

Unknown value type " + value.getValueType()

What it means

getState() maps a JsonValue's type to a parser Event; ARRAY, OBJECT, STRING, NUMBER, TRUE, FALSE, and NULL are handled, and any other ValueType falls into the default branch throwing this JsonException. With the standard JSON-P enum this is effectively unreachable, but it guards against exotic or future JsonValue implementations.

Source

Thrown at json-path/src/main/java/com/jayway/jsonpath/spi/mapper/JakartaMappingProvider.java:565

        private Event getState(JsonValue value) {
            switch (value.getValueType()) {
            case ARRAY:
                return Event.START_ARRAY;
            case OBJECT:
                return Event.START_OBJECT;
            case STRING:
                return Event.VALUE_STRING;
            case NUMBER:
                return Event.VALUE_NUMBER;
            case TRUE:
                return Event.VALUE_TRUE;
            case FALSE:
                return Event.VALUE_FALSE;
            case NULL:
                return Event.VALUE_NULL;
            default:
                throw new JsonException("Unknown value type " + value.getValueType());
            }
        }
    }

    private static abstract class JsonStructureScope implements Iterator<JsonValue> {
        /**
         * Returns current {@link JsonValue}, that the parser is pointing on. Before
         * the {@link #next()} method has been called, this returns {@code null}.
         *
         * @return JsonValue value object.
         */
        abstract JsonValue getValue();
    }

    private static class JsonArrayScope extends JsonStructureScope {
        private final Iterator<JsonValue> it;
        private JsonValue value;

View on GitHub (pinned to 62a4c9f0f6)

Solutions

1. Ensure all JsonValue instances come from the same JSON-P provider (check for multiple jsonp implementations on the classpath)
2. Convert foreign/custom JsonValue wrappers into standard JsonObject/JsonArray before mapping
3. Catch JsonException and inspect value.getValueType() to identify the offending implementation

Example fix

// before
JsonValue v = customLib.toJsonValue(data); // non-standard ValueType
adapter.next(); // JsonException: Unknown value type
// after
JsonValue v = Json.createObjectBuilder() // standard JSON-P API
    .add("data", customLib.toJsonString(data)).build();

switch (value.getValueType()) {
    case ARRAY: case OBJECT: case STRING: case NUMBER:
    case TRUE: case FALSE: case NULL: break;
    default: throw new IllegalStateException("Non-standard JsonValue type: " + value.getValueType());
}

boolean isStandardJsonValue(JsonValue v) {
    switch (v.getValueType()) {
        case ARRAY: case OBJECT: case STRING: case NUMBER:
        case TRUE: case FALSE: case NULL: return true;
        default: return false;
    }
}

try {
    mapper.map(value, typeRef, config);
} catch (JsonException e) {
    // unknown ValueType: value likely from a foreign JSON-P implementation
}

When it happens

Trigger: Passing a JsonValue whose getValueType() is not one of the seven standard JSON-P types — e.g. a custom or third-party JsonValue implementation with its own ValueType, or a value from a non-standard JSON-P version.

Common situations: Custom JsonValue implementations injected into the mapping pipeline; mixing JSON-P implementations (different providers on the classpath producing foreign JsonValue instances).

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• JSON-P adapter does not support getLocation()
• Cannot create JSON iterator for " + value
• InvalidJsonException
• InvalidJsonException
• InvalidJsonException

AI-assisted analysis of json-path/JsonPath@62a4c9f0f6 (2026-09-11). Data as JSON: /api/errors/7c5a1422fc1cb7d3. Report an issue: GitHub.