diff --git a/build-support/pulsar-test-service-start.sh b/build-support/pulsar-test-service-start.sh
index f8e26f9..4dd3163 100755
--- a/build-support/pulsar-test-service-start.sh
+++ b/build-support/pulsar-test-service-start.sh
@@ -25,7 +25,7 @@ cd $SRC_DIR
 
 ./build-support/pulsar-test-service-stop.sh
 
-CONTAINER_ID=$(docker run -i --user $(id -u) -p 8080:8080 -p 6650:6650 -p 8443:8443 -p 6651:6651 --rm --detach apachepulsar/pulsar:4.0.0 sleep 3600)
+CONTAINER_ID=$(docker run -i --user $(id -u) -p 8080:8080 -p 6650:6650 -p 8443:8443 -p 6651:6651 --rm --detach apachepulsar/pulsar:4.2.2 sleep 3600)
 echo $CONTAINER_ID > .tests-container-id.txt
 
 docker cp tests/test-conf $CONTAINER_ID:/pulsar/test-conf
diff --git a/tests/asyncio_test.py b/tests/asyncio_test.py
index 3cc1078..5394fba 100644
--- a/tests/asyncio_test.py
+++ b/tests/asyncio_test.py
@@ -201,7 +201,7 @@ async def test_create_producer_failure(self):
             await self._client.create_producer('tenant/ns/asyncio-test-send-failure')
             self.fail()
         except PulsarException as e:
-            self.assertEqual(e.error(), pulsar.Result.Timeout)
+            self.assertEqual(e.error(), pulsar.Result.TopicNotFound)
 
     async def test_send_failure(self):
         producer = await self._client.create_producer('asyncio-test-send-failure')
diff --git a/tests/pulsar_test.py b/tests/pulsar_test.py
index be817c5..93a6415 100755
--- a/tests/pulsar_test.py
+++ b/tests/pulsar_test.py
@@ -330,8 +330,11 @@ def test_deliver_at(self):
         client = Client(self.serviceUrl)
         consumer = client.subscribe("my-python-topic-deliver-at", "my-sub", consumer_type=ConsumerType.Shared)
         producer = client.create_producer("my-python-topic-deliver-at")
-        # Delay message in 1.1s
-        producer.send(b"hello", deliver_at=int(round(time.time() * 1000)) + 1100)
+        # Delay must exceed receive(1000) timeout plus broker early-delivery slack.
+        # Pulsar 4.2.x buckets deliverAt timestamps (trimLowerBit, ~512ms with 1s tick),
+        # so short delays (e.g. 1100ms) can be delivered immediately on broker >= 4.0.1.
+        delay_ms = 2500
+        producer.send(b"hello", deliver_at=int(round(time.time() * 1000)) + delay_ms)
 
         # Message should not be available in the next second
         with self.assertRaises(pulsar.Timeout):
@@ -349,8 +352,9 @@ def test_deliver_after(self):
         client = Client(self.serviceUrl)
         consumer = client.subscribe("my-python-topic-deliver-after", "my-sub", consumer_type=ConsumerType.Shared)
         producer = client.create_producer("my-python-topic-deliver-after")
-        # Delay message in 1.1s
-        producer.send(b"hello", deliver_after=timedelta(milliseconds=1100))
+        # Same margin as test_deliver_at; see comment there for broker 4.2.x bucketing.
+        delay_ms = 2500
+        producer.send(b"hello", deliver_after=timedelta(milliseconds=delay_ms))
 
         # Message should not be available in the next second
         with self.assertRaises(pulsar.Timeout):