apache/cassandra · error · InvalidTypeException

Not enough bytes to deserialize a map

Error message

Not enough bytes to deserialize a map

What it means

BufferUnderflowException-style InvalidTypeException from the map codec's deserialize: the input buffer does not contain enough bytes for the declared number of key/value pairs (size read via CodecUtils.readSize, then each entry via readValue). Truncated or corrupt serialized map data triggers it.

Solutions

1. Verify the bytes were produced by the same codec/protocol version on both ends
2. Check for truncation of the blob (column type mismatch, manual byte manipulation)
3. Re-write the data from the original source instead of patching the corrupted buffer

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/cql3/functions/types/TypeCodec.java:2516 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/4ee6556f8219c0ff. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/functions/types/TypeCodec.java:2516

            if (bytes == null || bytes.remaining() == 0) return newInstance(0);
            try
            {
                ByteBuffer input = bytes.duplicate();
                int n = CodecUtils.readSize(input, protocolVersion);
                Map<K, V> m = newInstance(n);
                for (int i = 0; i < n; i++)
                {
                    ByteBuffer kbb = CodecUtils.readValue(input, protocolVersion);
                    ByteBuffer vbb = CodecUtils.readValue(input, protocolVersion);
                    m.put(
                    keyCodec.deserialize(kbb, protocolVersion),
                    valueCodec.deserialize(vbb, protocolVersion));
                }
                return m;
            }
            catch (BufferUnderflowException e)
            {
                throw new InvalidTypeException("Not enough bytes to deserialize a map", e);
            }
        }

        /**
         * Return a new {@link Map} instance with the given estimated size.
         *
         * @param size The estimated size of the collection to create.
         * @return A new {@link Map} instance with the given estimated size.
         */
        protected abstract Map<K, V> newInstance(int size);
    }

    /**
     * This codec maps a CQL {@link DataType#map(DataType, DataType) map type} to a Java {@link Map}.
     * Implementation note: this codec returns mutable, non thread-safe {@link LinkedHashMap}
     * instances.
     */
    private static class MapCodec<K, V> extends AbstractMapCodec<K, V>

View on GitHub (pinned to 88fd0f6a0e)