apache/hadoop · error · IOException

Har: truncate not allowed

Error message

Har: truncate not allowed

What it means

truncate would change the length of a byte range inside a har part file, which is immutable, so the override throws 'Har: truncate not allowed'. Only read APIs are implemented on HarFileSystem.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HarFileSystem.java:769

    throw new IOException("Har: setReplication not allowed");
  }

  @Override
  public boolean rename(Path src, Path dst) throws IOException {
    throw new IOException("Har: rename not allowed");
  }

  @Override
  public FSDataOutputStream append(Path f) throws IOException {
    throw new IOException("Har: append not allowed");
  }

  /**
   * Not implemented.
   */
  @Override
  public boolean truncate(Path f, long newLength) throws IOException {
    throw new IOException("Har: truncate not allowed");
  }

  /**
   * Not implemented.
   */
  @Override
  public boolean delete(Path f, boolean recursive) throws IOException { 
    throw new IOException("Har: delete not allowed");
  }

  /**
   * liststatus returns the children of a directory 
   * after looking up the index files.
   */
  @Override
  public FileStatus[] listStatus(Path f) throws IOException {
    //need to see if the file is an index in file
    //get the filestatus of the archive directory

View on GitHub (pinned to 2add963021)

Solutions

1. Truncate the source file on the underlying HDFS and re-create the archive
2. If the whole archive is disposable, delete the .har directory via the underlying filesystem
3. Skip truncate calls for read-only filesystems by checking the scheme first

Example fix

// before
fs.truncate(new Path("har://hdfs-nn:8020/a/data.har/blob.bin"), 1024);

// after
hdfs.truncate(new Path("hdfs://nn:8020/a/data/blob.bin"), 1024);
// then rebuild the archive from the truncated tree

if ("har".equals(p.toUri().getScheme())) {
  throw new UnsupportedOperationException("truncate is not supported on har; rebuild the archive instead");
}

When it happens

Trigger: fs.truncate(harPath, newLength) on any har:// path — tools that shrink files or reclaim space, or generic file-management code that truncates instead of delete+recreate.

Common situations: Space-reclamation jobs sweeping all filesystems; ported code that relied on truncate semantics (e.g., HBase-style truncation) and now points at archived data.

Related errors

• Har: create not allowed.
• Har: append not allowed.
• Har: setReplication not allowed
• Har: rename not allowed
• Har: delete not allowed

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/8fa0345593471e22. Report an issue: GitHub.