apache/hadoop · error · StandbyException

Operation category {op} is not supported at {getRole()}

Error message

Operation category {op} is not supported at {getRole()}

What it means

Error "Operation category {op} is not supported at {getRole()}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/BackupNode.java:459

  @Override // NameNode
  protected NameNodeHAContext createHAContext() {
    return new BNHAContext();
  }

  private class BNHAContext extends NameNodeHAContext {
    @Override // NameNodeHAContext
    public void checkOperation(OperationCategory op)
        throws StandbyException {
      if (op == OperationCategory.UNCHECKED ||
          op == OperationCategory.CHECKPOINT) {
        return;
      }
      if (OperationCategory.JOURNAL != op &&
          !(OperationCategory.READ == op && !isRole(NamenodeRole.CHECKPOINT))) {
        String msg = "Operation category " + op
            + " is not supported at " + getRole();
        throw new StandbyException(msg);
      }
    }

    @Override // NameNodeHAContext
    public void prepareToStopStandbyServices() throws ServiceFailedException {
    }

    /**
     * Start services for BackupNode.
     * <p>
     * The following services should be muted
     * (not run or not pass any control commands to DataNodes)
     * on BackupNode:
     * {@link LeaseManager.Monitor} protected by SafeMode.
     * {@link BlockManager.RedundancyMonitor} protected by SafeMode.
     * {@link HeartbeatManager.Monitor} protected by SafeMode.
     * {@link DatanodeAdminManager.Monitor} need to prohibit refreshNodes().
     * {@link PendingReconstructionBlocks.PendingReconstructionMonitor}

View on GitHub (pinned to 2add963021)

Solutions

1. Issue the operation against the active NameNode instead of the BackupNode; BackupNode only supports read/checkpoint-related operation categories.

When it happens

Trigger: RPC for a write or unsupported operation category sent to a BackupNode/standby role instead of the active NameNode.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/d750f896756d8019. Report an issue: GitHub.