apache/hadoop · error · IOException

Cannot rename {absoluteSrc} under itself : {absoluteDst}

Error message

Cannot rename {absoluteSrc} under itself : {absoluteDst}

What it means

rename() blocks moving a directory into its own subtree: after both paths are made absolute, isParentOf(absoluteSrc, absoluteDst) detects that dst lives under src and throws IOException("Cannot rename <src> under itself : <dst>"). Such a move is logically self-contradictory, and FTP rename could not express it anyway.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ftp/FTPFileSystem.java:691

    Path workDir = new Path(client.printWorkingDirectory());
    Path absoluteSrc = makeAbsolute(workDir, src);
    Path absoluteDst = makeAbsolute(workDir, dst);
    if (!exists(client, absoluteSrc)) {
      throw new FileNotFoundException("Source path " + src + " does not exist");
    }
    if (isDirectory(absoluteDst)) {
      // destination is a directory: rename goes underneath it with the
      // source name
      absoluteDst = new Path(absoluteDst, absoluteSrc.getName());
    }
    if (exists(client, absoluteDst)) {
      throw new FileAlreadyExistsException("Destination path " + dst
          + " already exists");
    }
    URI parentSrc = absoluteSrc.getParent().toUri();
    URI parentDst = absoluteDst.getParent().toUri();
    if (isParentOf(absoluteSrc, absoluteDst)) {
      throw new IOException("Cannot rename " + absoluteSrc + " under itself"
      + " : "+ absoluteDst);
    }

    if (!parentSrc.toString().equals(parentDst.toString())) {
      throw new IOException("Cannot rename source: " + absoluteSrc
          + " to " + absoluteDst
          + " -"+ E_SAME_DIRECTORY_ONLY);
    }
    String from = absoluteSrc.getName();
    String to = absoluteDst.getName();
    client.changeWorkingDirectory(parentSrc.getPath());
    boolean renamed = client.rename(from, to);
    return renamed;
  }

  @Override
  public Path getWorkingDirectory() {
    // Return home directory always since we do not maintain state.

View on GitHub (pinned to 2add963021)

Solutions

Pick a destination outside the source subtree, e.g. a sibling directory (rename "/data" to "/data-old")
When nesting is required, copy-then-delete instead of rename: FileUtil.copy(fs, src, fs, dst, true, conf)
Guard path construction: reject any dst whose qualified path starts with the qualified src path + "/"

Example fix

// before
fs.rename(new Path("/data"), new Path("/data/archive"));  // IOException: under itself

// after
Path src = new Path("/data");
Path dst = new Path("/data-old");            // sibling, not a child of src
fs.rename(src, dst);

Defensive patterns

Strategy: validation

Validate before calling

// reject destinations inside the source subtree before calling rename
String s = src.makeQualified(fs).toUri().getPath();
String d = dst.makeQualified(fs).toUri().getPath();
if (d.startsWith(s.endsWith("/") ? s : s + "/")) {
  throw new IllegalArgumentException("dst is inside src: " + d);
}
fs.rename(src, dst);

Try / catch

catch IOException from rename, check message for "under itself", and re-run with a destination outside the subtree or fall back to copy+delete.

Prevention

Compose archive destinations as siblings, never children, of the source
Unit-test path-building helpers with src == dst-parent cases
For nesting moves, plan copy-then-delete from the start

When it happens

Trigger: rename("/data", "/data/archive/data") or any dst whose path has src as an ancestor; programmatic destination construction that nests the source inside itself (dst = src + "/old"); archive loops that build output paths under input paths.

Common situations: Archive/cleanup jobs deriving the destination from the source path (src + "/archive"); compaction flows moving a parent into a child; UI drag-and-drop letting users drop a folder into itself.

Related errors

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/28b3141e9f799025. Report an issue: GitHub.