Tencent/matrix · error · IllegalArgumentException

Field does not exists

Error message

Field <fieldName> does not exists

What it means

HahaHelper.fieldValue scans a heap-dump ClassInstance's field values for a field with the given name and throws IllegalArgumentException when no field matches. This means the analyzer expected an instance to have a named field (e.g. 'name', 'count', 'value') that is absent from the dumped class.

Solutions

1. Check hasField(values, fieldName) before calling fieldValue and handle the missing case gracefully.
2. Update Matrix/Haha to a version matching the Android version the dump was captured on.
3. Re-capture the heap dump on a supported OS version.
4. Log the instance's class name and available fields to diagnose the expected layout, then adjust the field-name constant.

Example fix

// before
String name = asString(fieldValue(values, "name"));
// after
String name = hasField(values, "name")
        ? asString(fieldValue(values, "name"))
        : "<unknown>";

if (!HahaHelper.hasField(values, fieldName)) { return fallback; }

try { return fieldValue(values, "name"); } catch (IllegalArgumentException e) { return defaultValue; }

When it happens

Trigger: Calling fieldValue with a field name that does not exist on the instance's class — e.g. reading 'value'/'count' from a String or wrapper class whose field layout differs across Android versions, or a renamed field when the class changed between OS versions.

Common situations: Analyzing dumps from Android versions where String internals changed (char[] value vs byte[] value, coder fields added); library updates renaming internal fields; parsing classes from a different JDK/ART than the analyzer expects.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Could not find char array in
• Unable to obtained scaled bitmap's dimensions
• Unexpected type for
• Unknown root type:
• Both of invoker and fieldName can not be null or nil.

AI-assisted analysis of Tencent/matrix@3b8293bd65 (2026-09-08). Data as JSON: /api/errors/11a451698ae4542b. Report an issue: GitHub.

Appendix: source

Thrown at matrix/matrix-android/matrix-resource-canary/matrix-resource-canary-analyzer/src/main/java/com/squareup/haha/perflib/HahaHelper.java:163

    }

    private static boolean isByteArray(Object value) {
        return value instanceof ArrayInstance && ((ArrayInstance) value).getArrayType() == Type.BYTE;
    }

    public static List<ClassInstance.FieldValue> classInstanceValues(Instance instance) {
        ClassInstance classInstance = (ClassInstance) instance;
        return classInstance.getValues();
    }

    @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
    public static <T> T fieldValue(List<ClassInstance.FieldValue> values, String fieldName) {
        for (ClassInstance.FieldValue fieldValue : values) {
            if (fieldValue.getField().getName().equals(fieldName)) {
                return (T) fieldValue.getValue();
            }
        }
        throw new IllegalArgumentException("Field " + fieldName + " does not exists");
    }

    public static boolean hasField(List<ClassInstance.FieldValue> values, String fieldName) {
        for (ClassInstance.FieldValue fieldValue : values) {
            if (fieldValue.getField().getName().equals(fieldName)) {
                //noinspection unchecked
                return true;
            }
        }
        return false;
    }

    public static int getArrayInstanceLength(ArrayInstance instance) {
        try {
            final java.lang.reflect.Field mLengthField = ArrayInstance.class.getDeclaredField("mLength");
            mLengthField.setAccessible(true);
            return mLengthField.getInt(instance);
        } catch (Throwable thr) {

View on GitHub (pinned to 3b8293bd65)