apache/hadoop · error · IncorrectVersionException

Unexpected version of data node. Reported: {}. Expecting = {

Error message

Unexpected version of data node. Reported: {}. Expecting = {}.

What it means

Error "Unexpected version of data node. Reported: {}. Expecting = {}." thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java:1899

    nn.checkHaStateChange(req);
    nn.transitionToObserver();
  }

  @Override // HAServiceProtocol
  public synchronized HAServiceStatus getServiceStatus() 
      throws AccessControlException, ServiceFailedException, IOException {
    checkNNStartup();
    return nn.getServiceStatus();
  }

  /**
   * Verify version.
   * @param version layout version
   * @throws IOException on layout version mismatch
   */
  void verifyLayoutVersion(int version) throws IOException {
    if (version != HdfsServerConstants.NAMENODE_LAYOUT_VERSION)
      throw new IncorrectVersionException(
          HdfsServerConstants.NAMENODE_LAYOUT_VERSION, version, "data node");
  }
  
  private void verifySoftwareVersion(DatanodeRegistration dnReg)
      throws IncorrectVersionException {
    String dnVersion = dnReg.getSoftwareVersion();
    if (VersionUtil.compareVersions(dnVersion, minimumDataNodeVersion) < 0) {
      IncorrectVersionException ive = new IncorrectVersionException(
          minimumDataNodeVersion, dnVersion, "DataNode", "NameNode");
      LOG.warn(ive.getMessage() + " DN: " + dnReg);
      throw ive;
    }
    String nnVersion = VersionInfo.getVersion();
    if (!dnVersion.equals(nnVersion)) {
      String messagePrefix = "Reported DataNode version '" + dnVersion +
          "' of DN " + dnReg + " does not match NameNode version '" +
          nnVersion + "'";
      long nnCTime = nn.getFSImage().getStorage().getCTime();

View on GitHub (pinned to 2add963021)

Solutions

1. Upgrade or downgrade the DataNode to a version compatible with the NameNode's expected version.

When it happens

Trigger: A DataNode registers or heartbeats with a software/layout version the NameNode does not accept.

Common situations: Mixing DataNode and NameNode versions during a partial or failed rolling upgrade.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/c9cc25968872f3b0. Report an issue: GitHub.