apache/hadoop · error · IOException

Har: mkdirs not allowed

Error message

Har: mkdirs not allowed

What it means

mkdirs throws 'Har: mkdirs not allowed' because a har has no writable namespace: directories exist only as index entries created by the archive tool. Any attempt to create directories inside har:// fails unconditionally.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HarFileSystem.java:824

  /**
   * return the top level archive path.
   */
  @Override
  public Path getHomeDirectory() {
    return new Path(uri.toString());
  }

  @Override
  public void setWorkingDirectory(Path newDir) {
    //does nothing.
  }
  
  /**
   * not implemented.
   */
  @Override
  public boolean mkdirs(Path f, FsPermission permission) throws IOException {
    throw new IOException("Har: mkdirs not allowed");
  }
  
  /**
   * not implemented.
   */
  @Override
  public void copyFromLocalFile(boolean delSrc, boolean overwrite,
      Path src, Path dst) throws IOException {
    throw new IOException("Har: copyfromlocalfile not allowed");
  }

  @Override
  public void copyFromLocalFile(boolean delSrc, boolean overwrite,
      Path[] srcs, Path dst) throws IOException {
    throw new IOException("Har: copyfromlocalfile not allowed");
  }

  /**

View on GitHub (pinned to 2add963021)

Solutions

1. Create directories on the underlying HDFS before running `hadoop archive`, not after
2. Point output-directory configuration at a writable filesystem (hdfs://)
3. Make 'ensure directory exists' helpers tolerate read-only filesystems instead of calling mkdirs blindly

Example fix

// before
if (!fs.exists(outDir)) { fs.mkdirs(outDir); } // outDir is har://

// after
if ("har".equals(outDir.toUri().getScheme())) {
  throw new IllegalArgumentException("cannot create directories under read-only " + outDir);
}
if (!fs.exists(outDir)) { fs.mkdirs(outDir); }

if ("har".equals(outDir.toUri().getScheme())) {
  throw new UnsupportedOperationException("cannot mkdirs under read-only har: " + outDir);
}
if (!fs.exists(outDir)) { fs.mkdirs(outDir); }

When it happens

Trigger: fs.mkdirs(harPath) — typically job setup that pre-creates output directories, or copy utilities that ensure the destination directory exists before writing.

Common situations: Frameworks whose setup step is `if (!fs.exists(outDir)) fs.mkdirs(outDir)` receiving a har:// output path; deployment scripts preparing directory trees across mixed filesystems.

Related errors

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

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/d7f1ddfc86ecdfc6. Report an issue: GitHub.