apache/hadoop · error · IOException

Cannot copy {} to its subdirectory {}

Error message

Cannot copy {} to its subdirectory {}

What it means

Error "Cannot copy {} to its subdirectory {}" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java:348

  }

  //
  // If the destination is a subdirectory of the source, then
  // generate exception
  //
  private static void checkDependencies(FileSystem srcFS,
                                        Path src,
                                        FileSystem dstFS,
                                        Path dst)
                                        throws IOException {
    if (srcFS == dstFS) {
      String srcq = srcFS.makeQualified(src).toString() + Path.SEPARATOR;
      String dstq = dstFS.makeQualified(dst).toString() + Path.SEPARATOR;
      if (dstq.startsWith(srcq)) {
        if (srcq.length() == dstq.length()) {
          throw new IOException("Cannot copy " + src + " to itself.");
        } else {
          throw new IOException("Cannot copy " + src + " to its subdirectory " +
                                dst);
        }
      }
    }
  }

  /**
   * Copy files between FileSystems.
   * @param srcFS src fs.
   * @param src src.
   * @param dstFS dst fs.
   * @param dst dst.
   * @param deleteSource delete source.
   * @param conf configuration.
   * @return if copy success true, not false.
   * @throws IOException raised on errors performing I/O.
   */
  public static boolean copy(FileSystem srcFS, Path src,

View on GitHub (pinned to 2add963021)

Solutions

1. Pick a destination outside the source directory tree.
2. Copy the source elsewhere first if the intent is a nested duplicate.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java:348 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/ce40d84c6aa01029. Report an issue: GitHub.