diff --git a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ClientCnx.java b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ClientCnx.java
index 35c41455e8987..ab02c89c298ed 100644
--- a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ClientCnx.java
+++ b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ClientCnx.java
@@ -925,6 +925,7 @@ public CompletableFuture<LookupDataResult> newLookup(ByteBuf request, long reque
             if (maxLookupRequestSemaphore.tryAcquire()) {
                 waitingLookupRequests.add(Pair.of(requestId, Pair.of(request, future)));
             } else {
+                request.release();
                 if (log.isDebugEnabled()) {
                     log.debug("{} Failed to add lookup-request into waiting queue", requestId);
                 }