prestodb/presto · error · ParquetDecodingException

not a valid mode

Error message

not a valid mode 

What it means

RepetitionLevelDecoder.readNext decodes repetition levels using either RLE or bit-packed mode, selected by the chunk header. A mode value outside the known enum means the repetition-level stream cannot be decoded and a ParquetDecodingException is thrown. This indicates malformed or unsupported repetition-level data in the column chunk.

Source

Thrown at presto-parquet/src/main/java/com/facebook/presto/parquet/batchreader/decoders/RepetitionLevelDecoder.java:93

                    break;
                }
                case PACKED: {
                    final int[] localBuffer = currentBuffer;
                    do {
                        int rlValue = localBuffer[currentOffsetPackedBuffer];
                        currentOffsetPackedBuffer = currentOffsetPackedBuffer + 1;
                        repetitionLevels.add(rlValue);
                        if (rlValue == 0) {
                            remainingToCopy--;
                        }
                        remaining--;
                    }
                    while (currentOffsetPackedBuffer < endOffsetPackedBuffer && remainingToCopy > 0);
                    currentCount = endOffsetPackedBuffer - currentOffsetPackedBuffer;
                    break;
                }
                default:
                    throw new ParquetDecodingException("not a valid mode " + mode);
            }
        }
        return batchSize - remainingToCopy;
    }

    @Override
    public long getRetainedSizeInBytes()
    {
        return INSTANCE_SIZE + sizeOf(currentBuffer);
    }

    private boolean ensureBlockAvailable()
            throws IOException
    {
        if (currentCount == 0) {
            if (!decode()) {
                return false;
            }

View on GitHub (pinned to 55bb57d202)

Solutions

1. Validate the file with parquet-tools and check the repetition-level encoding on the affected column
2. Re-write the file with a mainstream writer using standard RLE repetition levels
3. Upgrade the Presto parquet reader to a version that handles the writer's encoding
4. Confirm the file was not truncated in transfer (compare checksums) before filing a bug

Example fix

// before: reading a file whose nested column uses an unknown repetition-level mode
// after: rewrite the nested data with standard encodings
//   df.repartition(1).write.format("parquet").save("/fixed/path")

// parquet-tools meta file.parquet | grep <nested column>  # expect: RLE for repetition/definition levels

try {
    pageReader.readNextPage();
} catch (ParquetDecodingException e) {
    if (e.getMessage().contains("not a valid mode")) {
        log.error("Corrupt repetition-level stream in " + column); 
    }
    throw e;
}

When it happens

Trigger: readNext() hits the default branch of its mode switch because the repetition-level chunk header encodes an unknown mode value (not RLE, not PACKED_BIT_PACKED).

Common situations: Corrupted or truncated nested-column (list/map/struct) Parquet files; files written by non-standard writers using unsupported repetition-level encodings; version mismatch between the writer and the Presto parquet reader.

Related errors

• Unsupported Parquet encoding:
• Failed to decode.
• We didn't read correct number of definitionLevels
• Still remaining to be read in current batch.
• Corrupted Parquet file: extra %d values to be consumed when

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c3f2d6bd23c6f850. Report an issue: GitHub.