apache/cassandra · error · IOException

Corrupted input: expected byte 1, 2, 3, 4, 5 or 6; received

Error message

Corrupted input: expected byte 1, 2, 3, 4, 5 or 6; received 

What it means

The Unseekables serializer reads a kind byte and dispatches to one of six sub-serializers (RoutingKeys through FullRangeRoute, bytes 1-6). Any other byte throws IOException because the stream does not represent a valid serialized Unseekables. Causes are corruption, truncation/misalignment, or a peer encoding kinds this version does not know.

Source

Thrown at src/java/org/apache/cassandra/service/accord/serializers/KeySerializers.java:366

                    out.writeByte(5);
                    partialRangeRoute.serializeSubset((PartialRangeRoute)t, superset, out);
                    break;
                case FullRangeRoute:
                    out.writeByte(6);
                    fullRangeRoute.serializeSubset((FullRangeRoute)t, superset, out);
                    break;
            }
        }

        @Override
        public RS deserialize(DataInputPlus in) throws IOException
        {
            byte b = in.readByte();
            UnseekablesKind kind;
            RS result;
            switch (b)
            {
                default: throw new IOException("Corrupted input: expected byte 1, 2, 3, 4, 5 or 6; received " + b);
                case 1: kind = UnseekablesKind.RoutingKeys; result = (RS)routingKeys.deserialize(in); break;
                case 2: kind = UnseekablesKind.PartialKeyRoute; result = (RS)partialKeyRoute.deserialize(in); break;
                case 3: kind = UnseekablesKind.FullKeyRoute; result = (RS)fullKeyRoute.deserialize(in); break;
                case 4: kind = UnseekablesKind.RoutingRanges; result = (RS)ranges.deserialize(in); break;
                case 5: kind = UnseekablesKind.PartialRangeRoute; result = (RS)partialRangeRoute.deserialize(in); break;
                case 6: kind = UnseekablesKind.FullRangeRoute; result = (RS)fullRangeRoute.deserialize(in); break;
            }
            Invariants.require(permitted.contains(kind));
            return result;
        }

        public RS deserializeSubset(Unseekables<?> superset, DataInputPlus in) throws IOException
        {
            byte b = in.readByte();
            UnseekablesKind kind;
            RS result;
            switch (b)
            {

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Confirm cluster nodes run compatible versions so the UnseekablesKind encoding matches (finish rolling upgrade).
2. Log the received byte and cross-check against UnseekablesKind values to identify the mismatched encoder.
3. Look for earlier exceptions on the same connection that may have desynchronized the stream; reset the session.
4. If a new kind was added, update this serializer's switch and the documented byte range in the message.

try {
    Unseekables<?, ?> u = UnseekablesSerializer.deserialize(in, version);
} catch (IOException e) {
    if (e.getMessage().startsWith("Corrupted input")) {
        logger.warn("Corrupt Unseekables payload; discarding and resetting stream", e);
        // drop message / close connection to resynchronize
    } else throw e;
}

When it happens

Trigger: deserialize(DataInputPlus) reads a byte not in 1..6 while decoding an Unseekables/Route object, e.g. during Accord command/message deserialization.

Common situations: Version skew during rolling upgrades; corrupted network payload; stream misaligned by a prior deserialization bug; synthetic test data with a bad tag.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Corrupted input: expected byte 1, 2, 3, 4 or 5; received
• Unhandled CheckStatusReply kind:
• Corrupted input: expected byte 1 or 2, received " + b
• Invalid 64-bits double value, expecting 8 bytes but got
• Invalid 32-bits float value, expecting 4 bytes but got

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/b641d77e898f401f. Report an issue: GitHub.