apache/hadoop · error · IllegalArgumentException

Invalid entry, all mount points must start with / {}

Error message

Invalid entry, all mount points must start with / {}

What it means

Error "Invalid entry, all mount points must start with / {}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/store/records/MountTable.java:387

    return sb.toString();
  }

  @Override
  public SortedMap<String, String> getPrimaryKeys() {
    SortedMap<String, String> map = new TreeMap<>();
    map.put("sourcePath", this.getSourcePath());
    return map;
  }

  @Override
  public void validate() {
    super.validate();
    if (this.getSourcePath() == null || this.getSourcePath().length() == 0) {
      throw new IllegalArgumentException(
          ERROR_MSG_NO_SOURCE_PATH + this);
    }
    if (!this.getSourcePath().startsWith("/")) {
      throw new IllegalArgumentException(
          ERROR_MSG_MUST_START_WITH_BACK_SLASH + this);
    }
    if (this.getDestinations() == null || this.getDestinations().size() == 0) {
      throw new IllegalArgumentException(
          ERROR_MSG_NO_DEST_PATH_SPECIFIED + this);
    }
    for (RemoteLocation loc : getDestinations()) {
      String nsId = loc.getNameserviceId();
      if (nsId == null || nsId.length() == 0) {
        throw new IllegalArgumentException(
            ERROR_MSG_INVALID_DEST_NS + this);
      }
      if (loc.getDest() == null || loc.getDest().length() == 0) {
        throw new IllegalArgumentException(
            ERROR_MSG_INVALID_DEST_PATH + this);
      }
      if (!loc.getDest().startsWith("/")) {
        throw new IllegalArgumentException(

View on GitHub (pinned to 2add963021)

Solutions

1. Prefix the mount source path with '/', e.g. /data instead of data.
2. Correct the stored record so all mount points are absolute paths.

When it happens

Trigger: MountTable validation: a mount point path does not start with '/'.

Common situations: Admin supplied a relative path to dfsrouteradmin -add, or a record was written with a non-absolute source.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/2c8f148d6916c8a9. Report an issue: GitHub.