oracle/graal · error · IllegalArgumentException

Unknown registration

Error message

Unknown registration 

What it means

On the write path, registrationIndex looks up the CompilerInterfaceDeclarations.Registration's class in the codec's registrationIndices map; a miss throws IllegalArgumentException 'Unknown registration <class name>'. The registration table used by the codec instance does not contain the class of a value the writer is trying to encode as a registered (singleton or instance) object.

Source

Thrown at compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/hotspot/replaycomp/BinaryReplayCodec.java:1083

        out.write(value ? 1 : 0);
    }

    private static boolean readBooleanFlag(ObjectCopierInputStream in) throws IOException {
        int value = in.read();
        if (value < 0) {
            throw new EOFException();
        }
        return switch (value) {
            case 0 -> false;
            case 1 -> true;
            default -> throw new IOException("Invalid replay boolean flag " + value);
        };
    }

    private int registrationIndex(CompilerInterfaceDeclarations.Registration registration) {
        Integer index = registrationIndices.get(registration.clazz());
        if (index == null) {
            throw new IllegalArgumentException("Unknown registration " + registration.clazz().getName());
        }
        return index;
    }

    private static Object readSpecialSingleton(int kind) throws IOException {
        return switch (kind) {
            case SINGLETON_NULL_POINTER -> JavaConstant.NULL_POINTER;
            case SINGLETON_COMPRESSED_NULL -> HotSpotCompressedNullConstant.COMPRESSED_NULL;
            case SINGLETON_NO_SPECULATION -> SpeculationLog.NO_SPECULATION;
            case SINGLETON_ILLEGAL_VALUE_KIND -> ValueKind.Illegal;
            default -> throw new IOException("Unknown replay singleton kind " + kind);
        };
    }

    private Class<?> arrayComponentType(Object[] array) {
        Class<?> componentType = array.getClass().getComponentType();
        Class<?> registeredSupertype = declarations.findRegisteredSupertype(componentType);
        return (registeredSupertype != null) ? registeredSupertype : componentType;

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Ensure the value's class is registered in the same CompilerInterfaceDeclarations instance the codec was built from
2. Register the class before recording: declarations.register(clazz, singleton)
3. Re-create the codec after all registrations are performed, so registrationIndices is built from the full set

Example fix

// before
BinaryReplayCodec codec = new BinaryReplayCodec(declarations); // built too early
declarations.register(NewType.class, false);
codec.write(...); // Unknown registration NewType

// after
declarations.register(NewType.class, false);
BinaryReplayCodec codec = new BinaryReplayCodec(declarations); // built after registrations
codec.write(...);

static boolean registrationKnown(CompilerInterfaceDeclarations d, Class<?> clazz) {
    return d.findRegistration(clazz) != null; // or expose registrationIndices lookup
}

try {
    codec.writeValues(values);
} catch (IllegalArgumentException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("Unknown registration")) {
        // register the class and rebuild the codec, or skip recording
    } else throw e;
}

When it happens

Trigger: Recording a value whose Registration was obtained from a different CompilerInterfaceDeclarations configuration than the one the codec was constructed with; adding a new registered compiler type without adding it to the table the codec indexes.

Common situations: Split-brain registration configuration (some registrations registered in one declarations instance, codec built from another); extending the compiler interface types without updating the replay registration set.

Related errors

• No serializer for :
• Unexpected marker
• Unexpected architecture ${architecture}
• Unexpected architecture name ${archName}
• Unexpected register config ${registerConfig}

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/4f1d91cedd5d7362. Report an issue: GitHub.