diff --git a/pulsar-broker/src/main/java/org/apache/pulsar/client/impl/RawBatchConverter.java b/pulsar-broker/src/main/java/org/apache/pulsar/client/impl/RawBatchConverter.java
index dfa65d1995381..c11d5a3e37d90 100644
--- a/pulsar-broker/src/main/java/org/apache/pulsar/client/impl/RawBatchConverter.java
+++ b/pulsar-broker/src/main/java/org/apache/pulsar/client/impl/RawBatchConverter.java
@@ -135,7 +135,8 @@ public static Optional<RawMessage> rebatchMessage(RawMessage msg,
                                                       msg.getMessageIdData().getPartition(),
                                                       i);
                 if (!singleMessageMetadata.hasPartitionKey()) {
-                    if (retainNullKey) {
+                    // we may read compacted out message from compacted topic, which do not have partition key too.
+                    if (retainNullKey && !singleMessageMetadata.isCompactedOut()) {
                         messagesRetained++;
                         Commands.serializeSingleMessageInBatchWithPayload(singleMessageMetadata,
                                 singleMessagePayload, batchBuffer);