diff --git a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/TransactionMetaStoreHandler.java b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/TransactionMetaStoreHandler.java
index ebbfca0c3cb3f..0b5174a015118 100644
--- a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/TransactionMetaStoreHandler.java
+++ b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/TransactionMetaStoreHandler.java
@@ -167,6 +167,8 @@ public CompletableFuture<Void> connectionOpened(ClientCnx cnx) {
                     return null;
                 });
             } else {
+                LOG.warn("Can not connect to the transaction coordinator because the protocol version {} is "
+                                + "lower than 19", cnx.getRemoteEndpointProtocolVersion());
                 registerToConnection(cnx);
                 future.complete(null);
             }