apache/flink · error · IOException

Could not decode the dictionary for

Error message

Could not decode the dictionary for %s

What it means

Wraps an exception thrown while creating the dictionary-based data column reader from the dictionary page in NestedPrimitiveColumnReader's constructor; the chained cause explains why the dictionary could not be initialized for the column's primitive type.

Solutions

1. Address the cause reported by the error message: Could not decode the dictionary for the reported value
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Could not decode the dictionary for the reported value") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Could not decode the dictionary for the reported value.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Could not decode the dictionary for the reported value.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/b7d1f4b9b0a235d5. Report an issue: GitHub.

Appendix: source

Thrown at flink-formats/flink-parquet/src/main/java/org/apache/flink/formats/parquet/vector/reader/NestedPrimitiveColumnReader.java:141

        this.type = parquetType;
        this.pageReader = pageReader;
        this.maxDefLevel = descriptor.getMaxDefinitionLevel();
        this.isUtcTimestamp = isUtcTimestamp;
        this.logicalType = logicalType;

        DictionaryPage dictionaryPage = pageReader.readDictionaryPage();
        if (dictionaryPage != null) {
            try {
                this.dictionary =
                        ParquetDataColumnReaderFactory.getDataColumnReaderByTypeOnDictionary(
                                parquetType.asPrimitiveType(),
                                dictionaryPage
                                        .getEncoding()
                                        .initDictionary(descriptor, dictionaryPage),
                                isUtcTimestamp);
                this.isCurrentPageDictionaryEncoded = true;
            } catch (IOException e) {
                throw new IOException(
                        String.format("Could not decode the dictionary for %s", descriptor), e);
            }
        } else {
            this.dictionary = null;
            this.isCurrentPageDictionaryEncoded = false;
        }
    }

    // This won't call, will actually call readAndNewVector
    @Override
    public void readToVector(int readNumber, WritableColumnVector vector) throws IOException {
        throw new UnsupportedOperationException("This function should no be called.");
    }

    public WritableColumnVector readAndNewVector(int readNumber, WritableColumnVector vector)
            throws IOException {
        if (isFirstRow) {
            if (!readValue()) {

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