apache/cassandra · error · org.apache.cassandra.transport.ProtocolException

Invalid ByteBuf length " + length

Error message

Invalid ByteBuf length " + length

What it means

CBUtil.readValue(ByteBuf) treats a 4-byte length of -1 as null and -2 as the UNSET sentinel; any other negative length is invalid and throws ProtocolException "Invalid ByteBuf length <n>". Positive lengths are read normally. This rejects lengths outside the protocol's defined [-2, MAX] domain.

Solutions

1. Fix the sender so value lengths are only >=0, -1 (null), or -2 (unset)
2. Reconnect the session to resync the stream
3. Verify compression negotiation (lz4/snappy) matches on both ends
4. Capture frames to locate where the byte stream diverges

Example fix

// before
buf.writeInt(-3); // invalid sentinel
// after
buf.writeInt(-1); // null, or -2 for UNSET, or >=0 payload length

boolean isValidValueLength(int len) { return len >= 0 || len == -1 || len == -2; }

boolean isValidSentinel(int length) { return length == -1 || length == -2; }

try { ... } catch (ProtocolException e) { if (e.getMessage().startsWith("Invalid ByteBuf length")) { reconnectSession(); } else throw e; }

When it happens

Trigger: A serialized value field carries a length < -2 (e.g., corrupt int, bit-flipped frame, or misaligned read landing on non-length bytes).

Common situations: Stream desync after an earlier malformed message; memory corruption or buggy client writing garbage lengths; parsing compressed vs uncompressed frames inconsistently.

Related errors

• Cannot read value of length
• Not enough bytes to read a byte array preceded by its 2…
• Not enough bytes to read an UTF8 serialized string preceded…
• Not enough bytes to read an UTF8 serialized string preceded…
• Beta version of server used

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/5b6d224a4674e07c. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/transport/CBUtil.java:496

        ByteBuffer buffer = cb.nioBuffer(cb.readerIndex(), length);
        cb.skipBytes(length);
        return buffer;
    }

    public static ByteBuffer readBoundValue(ByteBuf cb, ProtocolVersion protocolVersion)
    {
        int length = cb.readInt();
        if (length < 0)
        {
            if (protocolVersion.isSmallerThan(ProtocolVersion.V4)) // backward compatibility for pre-version 4
                return null;
            if (length == -1)
                return null;
            else if (length == -2)
                return ByteBufferUtil.UNSET_BYTE_BUFFER;
            else
                throw new ProtocolException("Invalid ByteBuf length " + length);
        }
        return ByteBuffer.wrap(readRawBytes(cb, length));
    }

    public static void writeValue(byte[] bytes, ByteBuf cb)
    {
        if (bytes == null)
        {
            cb.writeInt(-1);
            return;
        }

        cb.writeInt(bytes.length);
        cb.writeBytes(bytes);
    }

    public static void writeValue(ByteBuffer bytes, ByteBuf cb)
    {

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