diff --git a/distribution/shell/src/assemble/LICENSE.bin.txt b/distribution/shell/src/assemble/LICENSE.bin.txt
index 9ed6074fbc4dd..df04985a3a880 100644
--- a/distribution/shell/src/assemble/LICENSE.bin.txt
+++ b/distribution/shell/src/assemble/LICENSE.bin.txt
@@ -331,10 +331,6 @@ The Apache Software License, Version 2.0
     - listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar
  * J2ObjC Annotations -- j2objc-annotations-1.3.jar
  * Netty Reactive Streams -- netty-reactive-streams-2.0.6.jar
- * Swagger
-    - swagger-annotations-1.6.10.jar
-    - swagger-core-1.6.10.jar
-    - swagger-models-1.6.10.jar
  * DataSketches
     - memory-0.8.3.jar
     - sketches-core-0.8.3.jar
diff --git a/pulsar-proxy/src/main/java/org/apache/pulsar/proxy/server/DefaultLookupProxyHandler.java b/pulsar-proxy/src/main/java/org/apache/pulsar/proxy/server/DefaultLookupProxyHandler.java
index b62d988904f63..15163dd7f6063 100644
--- a/pulsar-proxy/src/main/java/org/apache/pulsar/proxy/server/DefaultLookupProxyHandler.java
+++ b/pulsar-proxy/src/main/java/org/apache/pulsar/proxy/server/DefaultLookupProxyHandler.java
@@ -105,7 +105,7 @@ public void handleLookup(CommandLookupTopic lookup) {
                 log.debug("Lookup Request ID {} from {} rejected - {}.", clientRequestId, clientAddress,
                         throttlingErrorMessage);
             }
-            writeAndFlush(Commands.newLookupErrorResponse(ServerError.ServiceNotReady,
+            writeAndFlush(Commands.newLookupErrorResponse(ServerError.TooManyRequests,
                     throttlingErrorMessage, clientRequestId));
         }
     }
diff --git a/pulsar-proxy/src/test/java/org/apache/pulsar/proxy/server/ProxyLookupThrottlingTest.java b/pulsar-proxy/src/test/java/org/apache/pulsar/proxy/server/ProxyLookupThrottlingTest.java
index 4861117ef6ff5..1b63aa14dfe42 100644
--- a/pulsar-proxy/src/test/java/org/apache/pulsar/proxy/server/ProxyLookupThrottlingTest.java
+++ b/pulsar-proxy/src/test/java/org/apache/pulsar/proxy/server/ProxyLookupThrottlingTest.java
@@ -20,18 +20,26 @@
 
 import static org.mockito.Mockito.doReturn;
 import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.fail;
 
 import java.util.Optional;
+import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 
 import lombok.Cleanup;
 
+import org.apache.pulsar.broker.BrokerTestUtil;
 import org.apache.pulsar.broker.auth.MockedPulsarServiceBaseTest;
 import org.apache.pulsar.broker.authentication.AuthenticationService;
 import org.apache.pulsar.client.api.Producer;
 import org.apache.pulsar.client.api.PulsarClient;
 import org.apache.pulsar.client.api.Schema;
+import org.apache.pulsar.client.impl.BinaryProtoLookupService;
+import org.apache.pulsar.client.impl.ClientCnx;
+import org.apache.pulsar.client.impl.LookupService;
+import org.apache.pulsar.client.impl.PulsarClientImpl;
 import org.apache.pulsar.common.configuration.PulsarConfigurationLoader;
+import org.apache.pulsar.common.naming.TopicName;
 import org.apache.pulsar.metadata.impl.ZKMetadataStore;
 import org.mockito.Mockito;
 import org.testng.Assert;
@@ -112,4 +120,32 @@ public void testLookup() throws Exception {
 
         Assert.assertEquals(LookupProxyHandler.REJECTED_PARTITIONS_METADATA_REQUESTS.get(), 5.0d);
     }
+
+    @Test
+    public void testLookupThrottling() throws Exception {
+        PulsarClientImpl client = (PulsarClientImpl) PulsarClient.builder()
+                .serviceUrl(proxyService.getServiceUrl()).build();
+        String tpName = BrokerTestUtil.newUniqueName("persistent://public/default/tp");
+        LookupService lookupService = client.getLookup();
+        assertTrue(lookupService instanceof BinaryProtoLookupService);
+        ClientCnx lookupConnection = client.getCnxPool().getConnection(lookupService.resolveHost()).join();
+
+        // Make no permits to lookup.
+        Semaphore lookupSemaphore = proxyService.getLookupRequestSemaphore();
+        int availablePermits = lookupSemaphore.availablePermits();
+        lookupSemaphore.acquire(availablePermits);
+
+        // Verify will receive too many request exception, and the socket will not be closed.
+        try {
+            lookupService.getBroker(TopicName.get(tpName)).get();
+            fail("Expected too many request error.");
+        } catch (Exception ex) {
+            assertTrue(ex.getMessage().contains("Too many"));
+        }
+        assertTrue(lookupConnection.ctx().channel().isActive());
+
+        // cleanup.
+        lookupSemaphore.release(availablePermits);
+        client.close();
+    }
 }