{"record":{"id":"dee49c338f91723f","repo":"apache/hadoop","slug":"unregistered-server","errorCode":null,"errorMessage":"Unregistered server: {}","messagePattern":"Unregistered server: (.+?)","errorType":"exception","errorClass":"UnregisteredNodeException","httpStatus":null,"severity":"error","filePath":"hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java","lineNumber":1785,"sourceCode":"    namesystem.handleLifeline(nodeReg, report, dnCacheCapacity, dnCacheUsed,\n        xceiverCount, xmitsInProgress, failedVolumes, volumeFailureSummary);\n  }\n\n  /** \n   * Verifies the given registration.\n   * \n   * @param nodeReg node registration\n   * @throws UnregisteredNodeException if the registration is invalid\n   */\n  private void verifyRequest(NodeRegistration nodeReg) throws IOException {\n    // verify registration ID\n    final String id = nodeReg.getRegistrationID();\n    final String expectedID = namesystem.getRegistrationID();\n    if (!expectedID.equals(id)) {\n      LOG.warn(\"Registration IDs mismatched: the \"\n          + nodeReg.getClass().getSimpleName() + \" ID is \" + id\n          + \" but the expected ID is \" + expectedID);\n       throw new UnregisteredNodeException(nodeReg);\n    }\n  }\n\n  @Override // RefreshAuthorizationPolicyProtocol\n  public void refreshServiceAcl() throws IOException {\n    checkNNStartup();\n    if (!serviceAuthEnabled) {\n      throw new AuthorizationException(\"Service Level Authorization not enabled!\");\n    }\n\n    this.clientRpcServer.refreshServiceAcl(new Configuration(), new HDFSPolicyProvider());\n    if (this.serviceRpcServer != null) {\n      this.serviceRpcServer.refreshServiceAcl(new Configuration(), new HDFSPolicyProvider());\n    }\n    namesystem.logAuditEvent(true, \"refreshServiceAcl\", null);\n  }\n\n  @Override // RefreshAuthorizationPolicyProtocol","sourceCodeStart":1767,"sourceCodeEnd":1803,"githubUrl":"https://github.com/apache/hadoop/blob/2add9630210752f88ceb1bb74eb65e37bf41da8e/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java#L1767-L1803","documentation":"Error \"Unregistered server: {}\" thrown in apache/hadoop.","triggerScenarios":"A request arrives from a DataNode or service that has not registered with this NameNode.","commonSituations":"A misconfigured DataNode pointing at the wrong NameNode or cluster, or first-contact before registration.","solutions":["Register the DataNode/service with the NameNode (check clusterID/namespaceID match) before it sends requests."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"2add9630210752f88ceb1bb74eb65e37bf41da8e","analyzedAt":"2026-08-22T19:55:07.957Z","schemaVersion":2},"datasetVersion":"2026-08-22T20:17:22.307Z"}