apache/flink · error · IllegalArgumentException

Entropy length must be >= 0 when entropy injection key is se

Error message

Entropy length must be >= 0 when entropy injection key is set

What it means

Error "Entropy length must be >= 0 when entropy injection key is set" thrown in apache/flink.

Source

Thrown at flink-filesystems/flink-s3-fs-base/src/main/java/org/apache/flink/fs/s3/common/FlinkS3FileSystem.java:254

     * @param entropyInjectionKey The substring that will be replaced by entropy or removed.
     * @param entropyLength The number of random alphanumeric characters to inject as entropy.
     */
    public FlinkS3FileSystem(
            FileSystem hadoopS3FileSystem,
            @Nullable S5CmdConfiguration s5CmdConfiguration,
            String localTmpDirectory,
            @Nullable String entropyInjectionKey,
            int entropyLength,
            @Nullable S3AccessHelper s3UploadHelper,
            long s3uploadPartSize,
            int maxConcurrentUploadsPerStream) {

        super(hadoopS3FileSystem);

        this.s5CmdConfiguration = s5CmdConfiguration;

        if (entropyInjectionKey != null && entropyLength <= 0) {
            throw new IllegalArgumentException(
                    "Entropy length must be >= 0 when entropy injection key is set");
        }

        this.entropyInjectionKey = entropyInjectionKey;
        this.entropyLength = entropyLength;

        // recoverable writer parameter configuration initialization
        this.localTmpDir = Preconditions.checkNotNull(localTmpDirectory);
        this.tmpFileCreator = RefCountedTmpFileCreator.inDirectories(new File(localTmpDirectory));
        this.s3AccessHelper = s3UploadHelper;
        this.uploadThreadPool = Executors.newCachedThreadPool();

        checkArgument(s3uploadPartSize >= S3_MULTIPART_MIN_PART_SIZE);
        this.s3uploadPartSize = s3uploadPartSize;
        this.maxConcurrentUploadsPerStream = maxConcurrentUploadsPerStream;
        LOG.info("Created Flink S3 FS, s5Cmd configuration: {}", s5CmdConfiguration);
    }

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Address the cause reported by the error message: Entropy length must be >= 0 when entropy injection key is set
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Entropy length must be >= 0 when entropy injection key is set") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Entropy length must be >= 0 when entropy injection key is set.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Entropy length must be >= 0 when entropy injection key is set.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/db8c7cce092d3bf7. Report an issue: GitHub.