apache/hadoop · error · IllegalArgumentException

Message type is expected to be {} but got {}

Error message

Message type is expected to be {} but got {}

What it means

Error "Message type is expected to be {} but got {}" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/oncrpc/RpcMessage.java:65

      throw new IllegalArgumentException("Invalid message type " + messageType);
    }
    this.xid = xid;
    this.messageType = messageType;
  }

  public abstract XDR write(XDR xdr);

  public int getXid() {
    return xid;
  }

  public Type getMessageType() {
    return messageType;
  }

  protected void validateMessageType(Type expected) {
    if (expected != messageType) {
      throw new IllegalArgumentException("Message type is expected to be "
          + expected + " but got " + messageType);
    }
  }
}

View on GitHub (pinned to 2add963021)

Solutions

1. Align client and server expectations for the message type; a REPLY was expected but a different type arrived, indicating protocol mismatch or desynchronization.
2. Check for version mismatches between client and server RPC implementations.
3. Inspect the network for corrupted or interleaved RPC frames.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/oncrpc/RpcMessage.java:65 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/5813c03648f59c5d. Report an issue: GitHub.