diff --git a/pulsar-broker/src/main/java/org/apache/pulsar/broker/transaction/pendingack/impl/PendingAckHandleImpl.java b/pulsar-broker/src/main/java/org/apache/pulsar/broker/transaction/pendingack/impl/PendingAckHandleImpl.java
index 099cc5750888c..ed78feb453d1d 100644
--- a/pulsar-broker/src/main/java/org/apache/pulsar/broker/transaction/pendingack/impl/PendingAckHandleImpl.java
+++ b/pulsar-broker/src/main/java/org/apache/pulsar/broker/transaction/pendingack/impl/PendingAckHandleImpl.java
@@ -199,7 +199,7 @@ private void addIndividualAcknowledgeMessageRequest(TxnID txnID,
     public void internalIndividualAcknowledgeMessage(TxnID txnID, List<MutablePair<PositionImpl, Integer>> positions,
                                                      CompletableFuture<Void> completableFuture) {
         if (txnID == null) {
-            completableFuture.completeExceptionally(new NotAllowedException("Positions can not be null."));
+            completableFuture.completeExceptionally(new NotAllowedException("txnID can not be null."));
             return;
 
         }