apache/cassandra · error · IllegalStateException

buffer to uncompress into is not large enough; buf size =

Error message

buffer to uncompress into is not large enough; buf size = %d, buf offset = %d, target size = %s

What it means

Fired in EncryptionUtils.uncompress when the supplied output buffer is smaller than the compressed frame's declared outputLength and allowBufferResize is false. It is a guard against under-sized caller-provided buffers during encrypted-frame decompression (SSL streaming paths).

Solutions

1. Provide/resize the output buffer to at least the declared uncompressed length, or allow buffer resize (allowBufferResize=true)
2. Verify the compressed frame's declared outputLength matches the compressor's expectation

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/security/EncryptionUtils.java:203 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/7a6ab5eea2618fbc. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/security/EncryptionUtils.java:203

        int outputLength = inputBuffer.getInt();
        outputBuffer = ByteBufferUtil.ensureCapacity(outputBuffer, outputLength, allowBufferResize);
        compressor.uncompress(inputBuffer, outputBuffer);
        outputBuffer.position(0).limit(outputLength);

        return outputBuffer;
    }

    public static int uncompress(byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset, ICompressor compressor) throws IOException
    {
        int outputLength = readInt(input, inputOffset);
        inputOffset += 4;
        inputLength -= 4;

        if (output.length - outputOffset < outputLength)
        {
            String msg = String.format("buffer to uncompress into is not large enough; buf size = %d, buf offset = %d, target size = %s",
                                       output.length, outputOffset, outputLength);
            throw new IllegalStateException(msg);
        }

        return compressor.uncompress(input, inputOffset, inputLength, output, outputOffset);
    }

    private static int readInt(byte[] input, int inputOffset)
    {
        return  (input[inputOffset + 3] & 0xFF)
                | ((input[inputOffset + 2] & 0xFF) << 8)
                | ((input[inputOffset + 1] & 0xFF) << 16)
                | ((input[inputOffset] & 0xFF) << 24);
    }

    /**
     * A simple {@link java.nio.channels.Channel} adapter for ByteBuffers.
     */
    private static final class ChannelAdapter implements WritableByteChannel
    {

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