apache/hadoop · error · IOException

Invalid @class value in NodePlan JSON: {textValue}

Error message

Invalid @class value in NodePlan JSON: {textValue}

What it means

Error "Invalid @class value in NodePlan JSON: {textValue}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/planner/NodePlan.java:198

   *
   * @param node a node representing the root of tree structure
   * @throws IOException if any unexpected `@class` values are found - this is the
   * pre-existing exception type exposed by the calling code
   */
  private static void checkNodes(JsonNode node) throws IOException {
    if (node == null) {
      return;
    }

    // Check Node and Recurse into child nodes
    if (node.isObject()) {
      Iterator<Map.Entry<String, JsonNode>> fieldsIterator = node.fields();
      while (fieldsIterator.hasNext()) {
        Map.Entry<String, JsonNode> entry = fieldsIterator.next();
        if ("@class".equals(entry.getKey())) {
          String textValue = entry.getValue().asText();
          if (textValue != null && !textValue.isBlank() && !stepClassIsAllowed(textValue)) {
            throw new IOException("Invalid @class value in NodePlan JSON: " + textValue);
          }
        }
        checkNodes(entry.getValue());
      }
    } else if (node.isArray()) {
      for (int i = 0; i < node.size(); i++) {
        checkNodes(node.get(i));
      }
    }
  }

  /**
   * Returns a JSON representation of NodePlan.
   *
   * @return - JSON String
   * @throws IOException
   */
  public String toJson() throws IOException {

View on GitHub (pinned to 2add963021)

Solutions

1. Fix the @class field in the NodePlan JSON to a valid planner step class name.
2. Regenerate the plan file with the diskbalancer tool instead of editing it by hand.

When it happens

Trigger: DiskBalancer plan parsing when the JSON @class field names a class that is not a known NodePlan implementation.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/90567d1f403cc576. Report an issue: GitHub.