apache/hadoop · error · UnsupportedOperationException

Byte-buffer pread unsupported by ${className}

Error message

Byte-buffer pread unsupported by ${className}

What it means

Error "Byte-buffer pread unsupported by ${className}" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java:262

  public boolean hasCapability(String capability) {
    return StoreImplementationUtils.hasCapability(in, capability);
  }

  /**
   * String value. Includes the string value of the inner stream
   * @return the stream
   */
  @Override
  public String toString() {
    return super.toString() + ": " + in;
  }

  @Override
  public int read(long position, ByteBuffer buf) throws IOException {
    if (in instanceof ByteBufferPositionedReadable) {
      return ((ByteBufferPositionedReadable) in).read(position, buf);
    }
    throw new UnsupportedOperationException("Byte-buffer pread unsupported " +
        "by " + in.getClass().getCanonicalName());
  }

  /**
   * Delegate to the underlying stream.
   * @param position position within file
   * @param buf the ByteBuffer to receive the results of the read operation.
   * @throws IOException on a failure from the nested stream.
   * @throws UnsupportedOperationException if the inner stream does not
   * support this operation.
   */
  @Override
  public void readFully(long position, ByteBuffer buf) throws IOException {
    if (in instanceof ByteBufferPositionedReadable) {
      ((ByteBufferPositionedReadable) in).readFully(position, buf);
    } else {
      throw new UnsupportedOperationException("Byte-buffer pread " +
              "unsupported by " + in.getClass().getCanonicalName());

View on GitHub (pinned to 2add963021)

Solutions

1. Use positional byte-array pread instead of ByteBuffer pread.
2. Check hasCapability("in:preadbytebuffer") before use; fall back to regular pread when unsupported.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java:262 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/f70ec27dacf8cbcc. Report an issue: GitHub.