diff --git a/integration-tests/src/test/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerIntegrationTest.java b/integration-tests/src/test/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerIntegrationTest.java
index b9c66aa..0e62675 100644
--- a/integration-tests/src/test/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerIntegrationTest.java
+++ b/integration-tests/src/test/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerIntegrationTest.java
@@ -19,6 +19,7 @@
 import java.util.Collections;
 import java.util.Properties;
 import java.util.Random;
+import java.util.Set;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
@@ -30,6 +31,7 @@
 import org.apache.kafka.clients.producer.ProducerRecord;
 import org.apache.kafka.clients.producer.RecordMetadata;
 import org.apache.kafka.common.errors.RecordTooLargeException;
+import org.apache.kafka.common.errors.TimeoutException;
 import org.apache.kafka.common.serialization.ByteArraySerializer;
 import org.testng.Assert;
 import org.testng.annotations.AfterMethod;
@@ -196,6 +198,70 @@ public void uncaughtException(Thread t, Throwable e) {
     Assert.assertTrue(root instanceof RecordTooLargeException, root.getMessage());
   }
 
+  @Test
+  public void testProducerFlushAfterClose() throws Exception {
+    String topic = "testCloseFromProduceCallbackOnSenderThread";
+    createTopic(topic, 1);
+
+    Random random = new Random(666);
+    Properties extra = new Properties();
+    extra.setProperty(ProducerConfig.MAX_REQUEST_SIZE_CONFIG, "" + 1500);
+    extra.setProperty(ProducerConfig.ACKS_CONFIG, "-1");
+    extra.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, ByteArraySerializer.class.getCanonicalName());
+    extra.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, ByteArraySerializer.class.getCanonicalName());
+    Properties baseProducerConfig = getProducerProperties(extra);
+    LiKafkaInstrumentedProducerImpl<byte[], byte[]> producer = new LiKafkaInstrumentedProducerImpl<byte[], byte[]>(
+        baseProducerConfig,
+        Collections.emptyMap(),
+        (baseConfig, overrideConfig) -> new LiKafkaProducerImpl<byte[], byte[]>(LiKafkaClientsUtils.getConsolidatedProperties(baseConfig, overrideConfig)),
+        () -> "bogus",
+        10
+    );
+    byte[] key = new byte[500];
+    byte[] value = new byte[500];
+    random.nextBytes(key);
+    random.nextBytes(value);
+    ProducerRecord<byte[], byte[]> record = new ProducerRecord<>(topic, key, value);
+
+    producer.send(record);
+    producer.close(Duration.ofSeconds(0));
+    producer.flush(0, TimeUnit.MILLISECONDS);
+  }
+
+  @Test
+  public void testProducerFlushWithTimeoutException() throws Exception {
+    String topic = "testCloseFromProduceCallbackOnSenderThread";
+    createTopic(topic, 1);
+
+    Random random = new Random(666);
+    Properties extra = new Properties();
+    extra.setProperty(ProducerConfig.MAX_REQUEST_SIZE_CONFIG, "" + 1500);
+    extra.setProperty(ProducerConfig.ACKS_CONFIG, "-1");
+    extra.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, ByteArraySerializer.class.getCanonicalName());
+    extra.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, ByteArraySerializer.class.getCanonicalName());
+    Properties baseProducerConfig = getProducerProperties(extra);
+    LiKafkaInstrumentedProducerImpl<byte[], byte[]> producer = new LiKafkaInstrumentedProducerImpl<byte[], byte[]>(
+        baseProducerConfig,
+        Collections.emptyMap(),
+        (baseConfig, overrideConfig) -> new LiKafkaProducerImpl<byte[], byte[]>(LiKafkaClientsUtils.getConsolidatedProperties(baseConfig, overrideConfig)),
+        () -> "bogus",
+        10
+    );
+    byte[] key = new byte[500];
+    byte[] value = new byte[500];
+    random.nextBytes(key);
+    random.nextBytes(value);
+    ProducerRecord<byte[], byte[]> record = new ProducerRecord<>(topic, key, value);
+    producer.send(record);
+    // kill brokers
+    Set<Integer> brokerIds = super._brokers.keySet();
+    for (int id: brokerIds) {
+      super.killBroker(id);
+    }
+    producer.send(record);
+    Assert.assertThrows(TimeoutException.class, () -> producer.flush(0, TimeUnit.MILLISECONDS));
+  }
+
   private void createTopic(String topicName, int numPartitions) throws Exception {
     try (AdminClient adminClient = createRawAdminClient(null)) {
       adminClient.createTopics(Collections.singletonList(new NewTopic(topicName, numPartitions, (short) 1))).all().get(1, TimeUnit.MINUTES);
diff --git a/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerImpl.java b/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerImpl.java
index c686c61..5360eb7 100644
--- a/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerImpl.java
+++ b/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaInstrumentedProducerImpl.java
@@ -337,8 +337,6 @@ public Future<RecordMetadata> send(ProducerRecord<K, V> record, Callback callbac
 
   @Override
   public void flush() {
-    verifyOpen();
-
     delegateLock.readLock().lock();
     try {
       delegate.flush();
@@ -355,17 +353,21 @@ public void flush() {
    * If the underlying producer doesn't support a bounded flush, it will invoke the {@link #flush()}.
    */
   public void flush(long timeout, TimeUnit timeUnit) {
-    verifyOpen();
-
     delegateLock.readLock().lock();
     try {
       boolean useSeparateThreadForFlush = false;
       if (boundedFlushMethod != null) {
         try {
           boundedFlushMethod.invoke(delegate, timeout, timeUnit);
-        } catch (IllegalAccessException | InvocationTargetException e) {
-          throw new IllegalStateException("failed to invoke the bounded flush method", e);
-        }
+        } catch (IllegalAccessException illegalAccessException) {
+          throw new IllegalStateException("Failed to invoke the bounded flush method", illegalAccessException);
+        } catch (InvocationTargetException invocationTargetException) {
+            if (invocationTargetException.getCause() instanceof RuntimeException) {
+              throw (RuntimeException) invocationTargetException.getCause();
+            } else {
+              throw new IllegalStateException("Failed to invoke the bounded flush method", invocationTargetException);
+            }
+          }
       } else {
         useSeparateThreadForFlush = true;
       }
@@ -450,7 +452,6 @@ public void close(Duration timeout) {
         delegate.close(timeout.toMillis(), TimeUnit.MILLISECONDS);
       }
     } finally {
-      this.delegate = null;
       closeMdsClient();
     }
   }
diff --git a/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaProducerImpl.java b/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaProducerImpl.java
index cceddce..b1871f9 100644
--- a/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaProducerImpl.java
+++ b/li-apache-kafka-clients/src/main/java/com/linkedin/kafka/clients/producer/LiKafkaProducerImpl.java
@@ -423,8 +423,14 @@ public void flush(long timeout, TimeUnit timeUnit) {
     if (_boundedFlushMethod != null) {
       try {
         _boundedFlushMethod.invoke(_producer, timeout, timeUnit);
-      } catch (IllegalAccessException | InvocationTargetException e) {
-        throw new IllegalStateException("failed to invoke the bounded flush method", e);
+      } catch (IllegalAccessException illegalAccessException) {
+        throw new IllegalStateException("Failed to invoke the bounded flush method", illegalAccessException);
+      } catch (InvocationTargetException invocationTargetException) {
+        if (invocationTargetException.getCause() instanceof RuntimeException) {
+          throw (RuntimeException) invocationTargetException.getCause();
+        } else {
+          throw new IllegalStateException("Failed to invoke the bounded flush method", invocationTargetException);
+        }
       }
     } else {
       useSeparateThreadForFlush = true;